Part 10 of our Numerical Ability reviewer has 20 practice questions in the style of the Civil Service Exam. Answer them in order, read the explanation after each one, and check your score against the 80% passing mark at the end. Questions and choices are reshuffled every time you retake the part.
Start Part 10Sample questions from Part 10
Here are a few questions from this part. Take the full test to answer all 20 and get your score.
Sample question 1
5, 25, 7,______, 9, 19
- 23
- 22
- 25
- 32
Answer: 22
We are given a number sequence:
5, 25, 7, ___, 9, 19
We need to find the missing number (the blank).
Let's look for a pattern.
Step 1: Separate the sequence into two interleaved sequences:
1st, 3rd, 5th terms: 5, 7, 9
2nd, 4th, 6th terms: 25, ___, 19
Sequence A: 5, 7, 9
This is increasing by 2 each time.
Sequence B: 25, ___, 19
We need to find the middle term. Let's assume a consistent pattern.
Let’s test if it's decreasing with a pattern:
If it's decreasing from 25 to 19 over two steps:
Change = 25 - 19 = 6
So middle term = 25 - 3 = 22
✅ So the missing number is 22
Correct answer: (b) 22
5, 25, 7, ___, 9, 19
We need to find the missing number (the blank).
Let's look for a pattern.
Step 1: Separate the sequence into two interleaved sequences:
1st, 3rd, 5th terms: 5, 7, 9
2nd, 4th, 6th terms: 25, ___, 19
Sequence A: 5, 7, 9
This is increasing by 2 each time.
Sequence B: 25, ___, 19
We need to find the middle term. Let's assume a consistent pattern.
Let’s test if it's decreasing with a pattern:
If it's decreasing from 25 to 19 over two steps:
Change = 25 - 19 = 6
So middle term = 25 - 3 = 22
✅ So the missing number is 22
Correct answer: (b) 22
Sample question 2
62, 64,______, 32, 14,16
- 26
- 28
- 30
- 32
Answer: 30
✅ Final Pattern:
Odd positions (A): Subtracting halves:
62 → 30 (−32), 30 → 14 (−16)
Even positions (B): Dividing by 2:
64 → 32 → 16
✅ So 30 fits the pattern perfectly.
Odd positions (A): Subtracting halves:
62 → 30 (−32), 30 → 14 (−16)
Even positions (B): Dividing by 2:
64 → 32 → 16
✅ So 30 fits the pattern perfectly.
Sample question 3
100, 50, 52, 26, 28,______
- 30
- 32
- 14
- 16
Answer: 14
Step 1: Separate into two interleaved sequences:
Sequence A (1st, 3rd, 5th): 100, 52, 28
Sequence B (2nd, 4th, 6th): 50, 26, ___
Analyze Sequence A: 100, 52, 28
Find the differences:
100 → 52 = −48
52 → 28 = −24
Pattern: Subtracting by half each time
Next would be: 28 − 12 = 16 (if continued)
Analyze Sequence B: 50, 26, ___
50 → 26 = −24
If same halving continues:
26 − 12 = 14
✅ So the missing number is: 14
Sequence A (1st, 3rd, 5th): 100, 52, 28
Sequence B (2nd, 4th, 6th): 50, 26, ___
Analyze Sequence A: 100, 52, 28
Find the differences:
100 → 52 = −48
52 → 28 = −24
Pattern: Subtracting by half each time
Next would be: 28 − 12 = 16 (if continued)
Analyze Sequence B: 50, 26, ___
50 → 26 = −24
If same halving continues:
26 − 12 = 14
✅ So the missing number is: 14
Sample question 4
980, 392, 156.8,______, 25.088, 10.0352
- 62.72
- 63.85
- 65.04
- 60.28
Answer: 62.72
Step 1: Look at how each term relates to the previous one.
Check ratio of each consecutive term:
980 → 392
980
÷
392
=
2.5
980÷392=2.5
So:
980
×
2
5
=
392
980×
5
2
=392
392 → 156.8
392
×
2
5
=
156.8
392×
5
2
=156.8
So it appears we're multiplying by 2/5 (or 0.4) each time.
Let's verify this pattern:
156.8 × 0.4 = 62.72
62.72 × 0.4 = 25.088
25.088 × 0.4 = 10.0352
✅ Pattern confirmed: × 0.4 repeatedly.
✅ Missing number:
156.8 × 0.4 = 62.72
✔️ Correct answer: (a) 62.72
Check ratio of each consecutive term:
980 → 392
980
÷
392
=
2.5
980÷392=2.5
So:
980
×
2
5
=
392
980×
5
2
=392
392 → 156.8
392
×
2
5
=
156.8
392×
5
2
=156.8
So it appears we're multiplying by 2/5 (or 0.4) each time.
Let's verify this pattern:
156.8 × 0.4 = 62.72
62.72 × 0.4 = 25.088
25.088 × 0.4 = 10.0352
✅ Pattern confirmed: × 0.4 repeatedly.
✅ Missing number:
156.8 × 0.4 = 62.72
✔️ Correct answer: (a) 62.72
Sample question 5
113, 225, 449,_____, 1793
- 789
- 786
- 897
- 987
Answer: 897
Step 1: Look at the differences between consecutive terms:
225 − 113 = 112
449 − 225 = 224
Let the missing number be x
→ x − 449 = ?
→ 1793 − x = ?
Let’s suppose the difference is doubling:
112 → 224 = ×2
Let’s test next step:
224 × 2 = 448
→ 449 + 448 = 897
Check next step:
897 → 1793 = +896
→ 448 × 2 = 896 ✅
Pattern:
113
+112 → 225
+224 → 449
+448 → 897
+896 → 1793
✅ The differences are doubling: 112, 224, 448, 896
✔️ Correct answer: (c) 897
225 − 113 = 112
449 − 225 = 224
Let the missing number be x
→ x − 449 = ?
→ 1793 − x = ?
Let’s suppose the difference is doubling:
112 → 224 = ×2
Let’s test next step:
224 × 2 = 448
→ 449 + 448 = 897
Check next step:
897 → 1793 = +896
→ 448 × 2 = 896 ✅
Pattern:
113
+112 → 225
+224 → 449
+448 → 897
+896 → 1793
✅ The differences are doubling: 112, 224, 448, 896
✔️ Correct answer: (c) 897