**Number series test** is always there to challenge your knowledge and power of calculating things, mathematical logic and your perception for reasoning ability. It’s not so easy to solve a number series question impromptu, but you need to understand the hidden logic or clue behind the given numbers in that particular series. You need extensive practice to grasp the conception.

Below are *10 questions from this section with their proper answers*. Try hard to answer yourself. Very important if you are preparing hard for your upcoming competitive exams.

**Q1.** Which of the following number will replace the (?) mark and complete the series –

5, 10, 5, 20, 15, 40, 25, 80, ?

**Answer Option:**

a. 45

b. 50

c. 55

d. 60

### Answer

### Answer

### Explanation

### Explanation

(10×2 = 20 – 5 = 15), (20×2 = 40 – 15 = 25), (40×2 = 80 – 25 = 55)

So, the logic is – moving from L.H.S to R.H.S, if we multiply the 1st number by 2, then the next number appears. Once we subtract the 1st number from the 2nd, the 3rd or next number appears.

**Q2.** Which of the following number will replace the (?) mark and complete the series –

25, 10, 25, 15, 25, 22, 25, 31, 25, ?

**Answer Option:**

a. 35

b. 37

c. 42

d. 53

### Answer

### Answer

### Explanation

### Explanation

into an otherwise simple addition series that increases by 5, 7, 9, 11 and so on to get the final number 42.

**Q3.** Which of the following number will replace the (?) mark and complete the series –

9, 11, 16, 18, 23, 25, 30, 32, 37, ?

**Answer Option:**

a. 30

b. 39

c. 47

d. 61

### Answer

### Answer

### Explanation

### Explanation

**Q4.** Which of the following number will replace the (?) mark and complete the series –

13, 26, 20, 40, 34, 68, 62, ?

**Answer Option:**

a. 124

b. 90

c. 56

d. 144

### Answer

### Answer

### Explanation

### Explanation

**Q5.** Which of the following number in the below series is wrong?

4, 6, 12, 30, 75, 315, 1260

**Answer Option:**

a. 12

b. 30

c. 75

d. None of the above

### Answer

### Answer

### Explanation

### Explanation

**All the top 5 equations are solved in the following video:**

**Q6.** Which of the following number will replace the (?) mark and complete the series –

15, 21, 39, 77, 143, ?

**Answer Option:**

a. 245

b. 253

c. 287

d. 303

### Answer

### Answer

### Explanation

### Explanation

**Q7.** Which of the following number will replace the (?) mark and complete the series –

19, 26, 40, 68, 124, ?

**Answer Option:**

a. 180

b. 214

c. 223

d. 236

### Answer

### Answer

### Explanation

### Explanation

26 + 2 X 7 = 26 + 14 = 40

40 + 4 X 7 = 40 + 28 = 68

68 + 8 X 7 = 68 + 56 = 124

124 + 16 X 7 = 124 + 112= 236

**Q8.** Which of the following number will replace the (?) mark and complete the series –

3, 12, 30, 84, ?

**Answer Option:**

a. 180

b. 213

c. 246

d. 313

### Answer

### Answer

### Explanation

### Explanation

**Q9.** Which of the following number will replace the (?) mark and complete the series –

2, 4, 8, 32, 256,

**Answer Option:**

a. 589

b. 1123

c. 8192

d. None of the above

### Answer

### Answer

### Explanation

### Explanation

**Q10.** Which of the following number will replace the (?) mark and complete the series –

60, 64, 71, 87, 112, ?

**Answer Option:**

a. 134

b. 148

c. 156

d. 186

### Answer

### Answer

### Explanation

### Explanation

64 + (3×3) = 71

71 + (4×4) = 87

87 + (5×5) = 112

112 + (6×6) = 148

**Questions (Q6 to Q10) are solved in the following VIDEO:**