Lesson 20.1: Missing Numbers, Number Pyramids, and Math Riddles
Solve number pyramids, balance equations, and crack riddles.
⏱️ Reading Time: 15 mins
• ❓ 50 Interactive Practice Questions
#MathsPuzzles #NumberPyramids #MissingNumberPuzzles
Missing Numbers, Number Pyramids & Math Riddles
Math isn't just about formulas — it is a wonderful puzzle game full of mysteries, codes, and brain teasers!
9
4
5
Puzzle Rule:
4 + 5 = 9
Maths Puzzles: Number pyramid where the two bottom numbers add up to the top.
1. How Number Pyramids Work
In a number pyramid, any block is the sum of the two blocks directly beneath it!
If the bottom two blocks are 4 and 5, the block above them must be 4 + 5 = 9.
Mystery Detective: If the top block is 12 and one bottom block is 7, what is the other bottom block? 12 - 7 = 5!
2. Fun Math Riddles
Riddle: I am a two-digit number. I am greater than 30 and less than 40. The sum of my digits is 8. Who am I?
• Numbers between 30 and 40 have 3 tens: 30, 31, 32, 33, 34, 35...
• Digits must add to 8: 3 + ? = 8 → 5!
• The mystery number is 35!
Clue Hunting: Test each clue step by step until only one answer remains.
💡 Key Learning Takeaways
- In number pyramids, top = bottom left + bottom right.
- Math riddles use clues to narrow down possibilities.
- Puzzles build logical deduction and speed.
🎯 Key Learning Takeaways
Number pyramids and deductive logic.
📄 Printable Worksheets (10 Available)
Download ready-to-print PDFs for offline student practice with separate parent/teacher answer keys.
WL-G2-C20-W10
A4 • 15 Qs
Maths Puzzles and Reasoning — Worksheet 10
Curriculum Excellence & Final Review
WL-G2-C20-W09
A4 • 15 Qs
Maths Puzzles and Reasoning — Worksheet 9
Mastery Assessment & Progress Check
WL-G2-C20-W08
A4 • 15 Qs
Maths Puzzles and Reasoning — Worksheet 8
Mixed Review & Reinforcement
WL-G2-C20-W07
A4 • 15 Qs
Maths Puzzles and Reasoning — Worksheet 7
Everyday Applications & Story Maths
WL-G2-C20-W06
A4 • 15 Qs
Maths Puzzles and Reasoning — Worksheet 6
Critical Thinking & Deep Understanding
WL-G2-C20-W05
A4 • 15 Qs
Maths Puzzles and Reasoning — Worksheet 5
Speed Challenge & Quick Check
WL-G2-C20-W04
A4 • 15 Qs
Maths Puzzles and Reasoning — Worksheet 4
Problem Solving & Real-Life Stories
WL-G2-C20-W03
A4 • 15 Qs
Maths Puzzles and Reasoning — Worksheet 3
Hands-on Visual Activity & Matching
WL-G2-C20-W02
A4 • 15 Qs
Maths Puzzles and Reasoning — Worksheet 2
Essential Practice & Skill Builder
WL-G2-C20-W01
A4 • 15 Qs
Maths Puzzles and Reasoning — Worksheet 1
Foundational Concepts & Visual Exploration
✍️ Lesson Practice Questions (50 Questions)
Solve these real-world challenges online, test your understanding, and reveal instant step-by-step explanations.
1
Multiple Choice
Hard
1 Mark
What is the difference between (57 + 10) and (40 + 10)?
A
57
B
40
C
27
D
17
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
17
Step-by-Step Explanation:
Adding 10 to both numbers does not change their difference: (57 + 10) - (40 + 10) = 57 - 40 = 17.
2
Multiple Choice
Hard
1 Mark
A secret number plus 17 equals 57. If you double the secret number, what is the result?
A
40
B
42
C
114
D
80
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
80
Step-by-Step Explanation:
The secret number is 40. Doubling it gives 40 × 2 = 80.
3
Multiple Choice
Hard
1 Mark
If 40 + 17 = 57, what is 17 + 40?
A
58
B
57
C
17
D
40
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
57
Step-by-Step Explanation:
The order of addends does not affect the sum (commutative property).
4
Multiple Choice
Hard
1 Mark
Why is 57 greater than 40?
A
Because 57 includes 40 plus an additional 17 items
B
Because {tot} has a bigger first digit
C
Because {v1} is an even number
D
Numbers ending in 0 are always smaller
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Because 57 includes 40 plus an additional 17 items
Step-by-Step Explanation:
Adding a positive quantity always increases the total.
5
Multiple Choice
Medium
1 Mark
Sam evaluated 57 - 17 and wrote 74. What was Sam's mistake?
A
He added instead of subtracting
B
He divided the numbers
C
He multiplied by 2
D
He forgot the units place
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
He added instead of subtracting
Step-by-Step Explanation:
The minus sign means subtraction (taking away), but Sam performed addition.
6
Multiple Choice
Medium
1 Mark
A student claimed that 40 + 17 = 67 because 'we must add 10 to every answer'. Why is this student wrong?
A
Addition means combining only the given numbers without adding extra amounts
B
The student subtracted instead
C
The answer is 0
D
Addition is only for 1-digit numbers
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Addition means combining only the given numbers without adding extra amounts
Step-by-Step Explanation:
40 + 17 equals exactly 57.
7
Multiple Choice
Medium
1 Mark
Complete the pattern: 40, 45, 50, [ ? ].
A
52
B
54
C
60
D
55
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
55
Step-by-Step Explanation:
The pattern increases by 5. 50 + 5 = 55.
8
Multiple Choice
Medium
1 Mark
Find the missing number: 40 + [ ? ] = 57.
A
18
B
16
C
40
D
17
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
17
Step-by-Step Explanation:
Missing value is 17 because 40 + 17 = 57.
9
Multiple Choice
Medium
1 Mark
In a school garden, there are 40 yellow marigolds and 17 purple petunias. How many flowers are blooming in total?
A
40 flowers
B
57 flowers
C
17 flowers
D
62 flowers
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
57 flowers
Step-by-Step Explanation:
40 + 17 = 57 flowers.
10
Multiple Choice
Medium
1 Mark
A school library received 57 new graphic novels. Students checked out 17 novels on Monday. How many new novels are still on the shelf?
A
40 novels
B
41 novels
C
17 novels
D
57 novels
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
40 novels
Step-by-Step Explanation:
57 - 17 = 40 novels remaining.
11
Multiple Choice
Medium
1 Mark
A baker packed 40 apple pies in the morning and 17 cherry pies in the afternoon. How many pies did the baker pack in all?
A
59 pies
B
57 pies
C
40 pies
D
55 pies
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
57 pies
Step-by-Step Explanation:
40 + 17 = 57 pies in total.
12
Multiple Choice
Easy
1 Mark
What number is 10 more than 40?
A
60
B
30
C
41
D
50
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
50
Step-by-Step Explanation:
40 + 10 = 50.
13
Multiple Choice
Easy
1 Mark
Which comparison is correct: 57 [ ? ] 52?
A
>
B
<
C
≈
D
=
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
>
Step-by-Step Explanation:
57 is greater than 52.
14
Multiple Choice
Easy
1 Mark
Calculate: 57 - 17 = ?
A
40
B
41
C
17
D
39
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
40
Step-by-Step Explanation:
57 - 17 = 40.
15
Multiple Choice
Easy
1 Mark
In Chapter 'Maths Puzzles and Reasoning', calculate: 40 + 17 = ?
A
56
B
57
C
58
D
67
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
57
Step-by-Step Explanation:
40 + 17 = 57.
16
Multiple Choice
Hard
1 Mark
What is the difference between (47 + 10) and (33 + 10)?
A
33
B
47
C
24
D
14
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
14
Step-by-Step Explanation:
Adding 10 to both numbers does not change their difference: (47 + 10) - (33 + 10) = 47 - 33 = 14.
17
Multiple Choice
Hard
1 Mark
A secret number plus 14 equals 47. If you double the secret number, what is the result?
A
35
B
33
C
94
D
66
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
66
Step-by-Step Explanation:
The secret number is 33. Doubling it gives 33 × 2 = 66.
18
Multiple Choice
Hard
1 Mark
If 33 + 14 = 47, what is 14 + 33?
A
33
B
48
C
14
D
47
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
47
Step-by-Step Explanation:
The order of addends does not affect the sum (commutative property).
19
Multiple Choice
Hard
1 Mark
Why is 47 greater than 33?
A
Because 47 includes 33 plus an additional 14 items
B
Numbers ending in 0 are always smaller
C
Because {tot} has a bigger first digit
D
Because {v1} is an even number
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Because 47 includes 33 plus an additional 14 items
Step-by-Step Explanation:
Adding a positive quantity always increases the total.
20
Multiple Choice
Medium
1 Mark
Sam evaluated 47 - 14 and wrote 61. What was Sam's mistake?
A
He divided the numbers
B
He added instead of subtracting
C
He forgot the units place
D
He multiplied by 2
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
He added instead of subtracting
Step-by-Step Explanation:
The minus sign means subtraction (taking away), but Sam performed addition.
21
Multiple Choice
Medium
1 Mark
A student claimed that 33 + 14 = 57 because 'we must add 10 to every answer'. Why is this student wrong?
A
The answer is 0
B
Addition means combining only the given numbers without adding extra amounts
C
The student subtracted instead
D
Addition is only for 1-digit numbers
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Addition means combining only the given numbers without adding extra amounts
Step-by-Step Explanation:
33 + 14 equals exactly 47.
22
Multiple Choice
Medium
1 Mark
Complete the pattern: 33, 38, 43, [ ? ].
A
48
B
53
C
47
D
45
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
48
Step-by-Step Explanation:
The pattern increases by 5. 43 + 5 = 48.
23
Multiple Choice
Medium
1 Mark
Find the missing number: 33 + [ ? ] = 47.
A
13
B
33
C
15
D
14
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
14
Step-by-Step Explanation:
Missing value is 14 because 33 + 14 = 47.
24
Multiple Choice
Medium
1 Mark
In a school garden, there are 33 yellow marigolds and 14 purple petunias. How many flowers are blooming in total?
A
14 flowers
B
52 flowers
C
33 flowers
D
47 flowers
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
47 flowers
Step-by-Step Explanation:
33 + 14 = 47 flowers.
25
Multiple Choice
Medium
1 Mark
A school library received 47 new graphic novels. Students checked out 14 novels on Monday. How many new novels are still on the shelf?
A
33 novels
B
34 novels
C
47 novels
D
14 novels
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
33 novels
Step-by-Step Explanation:
47 - 14 = 33 novels remaining.
26
Multiple Choice
Medium
1 Mark
A baker packed 33 apple pies in the morning and 14 cherry pies in the afternoon. How many pies did the baker pack in all?
A
33 pies
B
47 pies
C
49 pies
D
45 pies
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
47 pies
Step-by-Step Explanation:
33 + 14 = 47 pies in total.
27
Multiple Choice
Easy
1 Mark
What number is 10 more than 33?
A
23
B
43
C
53
D
34
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
43
Step-by-Step Explanation:
33 + 10 = 43.
28
Multiple Choice
Easy
1 Mark
Which comparison is correct: 47 [ ? ] 42?
A
<
B
=
C
≈
D
>
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
>
Step-by-Step Explanation:
47 is greater than 42.
29
Multiple Choice
Easy
1 Mark
Calculate: 47 - 14 = ?
A
33
B
32
C
34
D
14
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
33
Step-by-Step Explanation:
47 - 14 = 33.
30
Multiple Choice
Easy
1 Mark
In Chapter 'Maths Puzzles and Reasoning', calculate: 33 + 14 = ?
A
57
B
48
C
46
D
47
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
47
Step-by-Step Explanation:
33 + 14 = 47.
31
Multiple Choice
Hard
1 Mark
What is the difference between (62 + 10) and (26 + 10)?
A
46
B
62
C
36
D
26
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
36
Step-by-Step Explanation:
Adding 10 to both numbers does not change their difference: (62 + 10) - (26 + 10) = 62 - 26 = 36.
32
Multiple Choice
Hard
1 Mark
A secret number plus 36 equals 62. If you double the secret number, what is the result?
A
28
B
26
C
124
D
52
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
52
Step-by-Step Explanation:
The secret number is 26. Doubling it gives 26 × 2 = 52.
33
Multiple Choice
Hard
1 Mark
If 26 + 36 = 62, what is 36 + 26?
A
26
B
63
C
62
D
36
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
62
Step-by-Step Explanation:
The order of addends does not affect the sum (commutative property).
34
Multiple Choice
Hard
1 Mark
Why is 62 greater than 26?
A
Numbers ending in 0 are always smaller
B
Because 62 includes 26 plus an additional 36 items
C
Because {tot} has a bigger first digit
D
Because {v1} is an even number
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Because 62 includes 26 plus an additional 36 items
Step-by-Step Explanation:
Adding a positive quantity always increases the total.
35
Multiple Choice
Medium
1 Mark
Sam evaluated 62 - 36 and wrote 98. What was Sam's mistake?
A
He divided the numbers
B
He added instead of subtracting
C
He multiplied by 2
D
He forgot the units place
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
He added instead of subtracting
Step-by-Step Explanation:
The minus sign means subtraction (taking away), but Sam performed addition.
36
Multiple Choice
Medium
1 Mark
A student claimed that 26 + 36 = 72 because 'we must add 10 to every answer'. Why is this student wrong?
A
Addition means combining only the given numbers without adding extra amounts
B
The student subtracted instead
C
Addition is only for 1-digit numbers
D
The answer is 0
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Addition means combining only the given numbers without adding extra amounts
Step-by-Step Explanation:
26 + 36 equals exactly 62.
37
Multiple Choice
Medium
1 Mark
Complete the pattern: 26, 31, 36, [ ? ].
A
41
B
40
C
38
D
46
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
41
Step-by-Step Explanation:
The pattern increases by 5. 36 + 5 = 41.
38
Multiple Choice
Medium
1 Mark
Find the missing number: 26 + [ ? ] = 62.
A
26
B
36
C
37
D
35
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
36
Step-by-Step Explanation:
Missing value is 36 because 26 + 36 = 62.
39
Multiple Choice
Medium
1 Mark
In a school garden, there are 26 yellow marigolds and 36 purple petunias. How many flowers are blooming in total?
A
62 flowers
B
26 flowers
C
36 flowers
D
67 flowers
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
62 flowers
Step-by-Step Explanation:
26 + 36 = 62 flowers.
40
Multiple Choice
Medium
1 Mark
A school library received 62 new graphic novels. Students checked out 36 novels on Monday. How many new novels are still on the shelf?
A
27 novels
B
26 novels
C
36 novels
D
62 novels
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
26 novels
Step-by-Step Explanation:
62 - 36 = 26 novels remaining.
41
Multiple Choice
Medium
1 Mark
A baker packed 26 apple pies in the morning and 36 cherry pies in the afternoon. How many pies did the baker pack in all?
A
62 pies
B
64 pies
C
26 pies
D
60 pies
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
62 pies
Step-by-Step Explanation:
26 + 36 = 62 pies in total.
42
Multiple Choice
Easy
1 Mark
What number is 10 more than 26?
A
46
B
27
C
36
D
16
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
36
Step-by-Step Explanation:
26 + 10 = 36.
43
Multiple Choice
Easy
1 Mark
Which comparison is correct: 62 [ ? ] 57?
A
>
B
≈
C
<
D
=
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
>
Step-by-Step Explanation:
62 is greater than 57.
44
Multiple Choice
Easy
1 Mark
Calculate: 62 - 36 = ?
A
26
B
25
C
27
D
36
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
26
Step-by-Step Explanation:
62 - 36 = 26.
45
Multiple Choice
Easy
1 Mark
In Chapter 'Maths Puzzles and Reasoning', calculate: 26 + 36 = ?
A
72
B
62
C
63
D
61
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
62
Step-by-Step Explanation:
26 + 36 = 62.
46
Multiple Choice
Hard
1 Mark
What is the difference between (52 + 10) and (19 + 10)?
A
43
B
52
C
33
D
19
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
33
Step-by-Step Explanation:
Adding 10 to both numbers does not change their difference: (52 + 10) - (19 + 10) = 52 - 19 = 33.
47
Multiple Choice
Hard
1 Mark
A secret number plus 33 equals 52. If you double the secret number, what is the result?
A
38
B
21
C
104
D
19
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
38
Step-by-Step Explanation:
The secret number is 19. Doubling it gives 19 × 2 = 38.
48
Multiple Choice
Hard
1 Mark
If 19 + 33 = 52, what is 33 + 19?
A
52
B
53
C
33
D
19
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
52
Step-by-Step Explanation:
The order of addends does not affect the sum (commutative property).
49
Multiple Choice
Hard
1 Mark
Why is 52 greater than 19?
A
Because 52 includes 19 plus an additional 33 items
B
Because {tot} has a bigger first digit
C
Numbers ending in 0 are always smaller
D
Because {v1} is an even number
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
Because 52 includes 19 plus an additional 33 items
Step-by-Step Explanation:
Adding a positive quantity always increases the total.
50
Multiple Choice
Medium
1 Mark
Sam evaluated 52 - 33 and wrote 85. What was Sam's mistake?
A
He divided the numbers
B
He multiplied by 2
C
He added instead of subtracting
D
He forgot the units place
💡 Click to View Correct Answer & Explanation ▼
Correct Answer:
He added instead of subtracting
Step-by-Step Explanation:
The minus sign means subtraction (taking away), but Sam performed addition.