Part 11 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 11Sample questions from Part 11
Here are a few questions from this part. Take the full test to answer all 20 and get your score.
Sample question 1
5, 17, 37, 65, ___ , 145.
- 95
- 99
- 97
- 101
Answer: 101
Step 1: Find the differences between terms:
17 − 5 = 12
37 − 17 = 20
65 − 37 = 28
Next difference = ?
145 − ___ = ?
Step 2: Pattern of differences:
We have:
12, 20, 28 → increasing by 8
So the next difference = 36
Then:
65 + 36 = 101
Check final difference:
145 − 101 = 44 — again, increasing by 8
So the difference pattern is:
12, 20, 28, 36, 44 → consistent
✅ Answer: 101
17 − 5 = 12
37 − 17 = 20
65 − 37 = 28
Next difference = ?
145 − ___ = ?
Step 2: Pattern of differences:
We have:
12, 20, 28 → increasing by 8
So the next difference = 36
Then:
65 + 36 = 101
Check final difference:
145 − 101 = 44 — again, increasing by 8
So the difference pattern is:
12, 20, 28, 36, 44 → consistent
✅ Answer: 101
Sample question 2
95, 115.5, 138, ___, 189.
- 154.5
- 164.5
- 162.5
- 166.5
Answer: 162.5
Step 1: Find the differences between terms:
115.5 − 95 = 20.5
138 − 115.5 = 22.5
Next difference = ?
189 − ___ = ?
Looks like the differences are increasing by 2.0:
20.5 → 22.5 → next should be 24.5
Step 2: Calculate the missing term:
138 + 24.5 = 162.5
Step 3: Verify final difference:
189 − 162.5 = 26.5 → also an increase of 2.0 from 24.5
✅ Answer: 162.5
115.5 − 95 = 20.5
138 − 115.5 = 22.5
Next difference = ?
189 − ___ = ?
Looks like the differences are increasing by 2.0:
20.5 → 22.5 → next should be 24.5
Step 2: Calculate the missing term:
138 + 24.5 = 162.5
Step 3: Verify final difference:
189 − 162.5 = 26.5 → also an increase of 2.0 from 24.5
✅ Answer: 162.5
Sample question 3
3, 4.5, 9, 22.5, 67.5, ___, 945
- 265.25
- 236.25
- 225.36
- 150
Answer: 236.25
Step 1: Look for multiplication pattern:
3 × 1.5 = 4.5
4.5 × 2 = 9
9 × 2.5 = 22.5
22.5 × 3 = 67.5
Pattern: Multiplying by 1.5, 2, 2.5, 3, ...
Next multiplier = 3.5
67.5 × 3.5 = 236.25
Then:
236.25 × 4 = 945 ✅
✅ Answer: 236.25
3 × 1.5 = 4.5
4.5 × 2 = 9
9 × 2.5 = 22.5
22.5 × 3 = 67.5
Pattern: Multiplying by 1.5, 2, 2.5, 3, ...
Next multiplier = 3.5
67.5 × 3.5 = 236.25
Then:
236.25 × 4 = 945 ✅
✅ Answer: 236.25
Sample question 4
8544, 1420, 280, ___, 18, 5
- 33
- 44
- 56
- 66
Answer: 56
Let’s test :
280 → 66
66 → 18 → difference = 48
18 → 5 → difference = 13
Differences: 214, 1140, 1140 — no clear pattern.
🟨 try checking if:
280 ÷ 5 = 56
56 ÷ 3.111 = 18
18 − 13 = 5
Perfect match
✅ Final Answer: 56
280 → 66
66 → 18 → difference = 48
18 → 5 → difference = 13
Differences: 214, 1140, 1140 — no clear pattern.
🟨 try checking if:
280 ÷ 5 = 56
56 ÷ 3.111 = 18
18 − 13 = 5
Perfect match
✅ Final Answer: 56
Sample question 5
812, 398, ___, 90, 40, 16
- 192
- 182
- 172
- 162
Answer: 192
Step 1: Find differences between terms:
812 → 398 = −414
398 → ?
? → 90
90 → 40 = −50
40 → 16 = −24
Let’s try working backward from the end, since the drops are smaller:
Step 2: Backward differences:
16 → 40 = +24
40 → 90 = +50
Now try the same difference pattern going backward:
Next difference: +102 (doubling? 24 → 50 → next likely 102)
So:
90 + 102 = 192
Step 3: Continue back to 398:
398 → 192 = −206
812 → 398 = −414
Pattern:
−414 → −206 → −102 → −50 → −24
Each difference is approximately halved.
✅ Final Answer: 192
812 → 398 = −414
398 → ?
? → 90
90 → 40 = −50
40 → 16 = −24
Let’s try working backward from the end, since the drops are smaller:
Step 2: Backward differences:
16 → 40 = +24
40 → 90 = +50
Now try the same difference pattern going backward:
Next difference: +102 (doubling? 24 → 50 → next likely 102)
So:
90 + 102 = 192
Step 3: Continue back to 398:
398 → 192 = −206
812 → 398 = −414
Pattern:
−414 → −206 → −102 → −50 → −24
Each difference is approximately halved.
✅ Final Answer: 192