Question 1

105, 85, 60, 30, 0, - 45, - 90?

Accepted Answer

Subtract 20, 25, 30, 35, 40, 45 from successive numbers. So 0 is wrong.

Question 2

8, 7, 11, 12, 14, 17, 17, 22, (...)?

Accepted Answer

There are two series (8, 11, 14, 17, 20) and (7, 12, 17, 22). Increasing by 3 and 5 respectively.

Question 3

8, 24, 12, 36, 18, 54, (...)?

Accepted Answer

Number are alternately multiplied by 3 and divided by 2. So, next number = 54 / 2 = 27.

Question 4

15, 31, 63, 127, 255, (...)?

Accepted Answer

Each number is double the preceding one plus 1. So, the next number is (255 x 2) + 1 = 511.

Question 5

3, 7, 6, 5, 9, 3, 12, 1, 15, (...)?

Accepted Answer

There are two series, beginning respectively with 3 and 7. In one 3 is added and in another 2 is subtracted. The next number is 1 - 2 = - 1.

Question 6

16, 33, 65, 131, 261, (...)?

Accepted Answer

Each number is twice the preceding one with 1 added or subtracted alternately. So, the next number is (2 x 261 + 1) = 523.

Question 7

445, 221, 109, 46, 25, 11, 4?

Accepted Answer

Go on subtracting 3 and dividing the result by 2 to obtain the next number. Clearly, 46 is wrong.

Question 8

19, 26, 33, 46, 59, 74, 91?

Accepted Answer

Go on adding 7, 9, 11, 13, 15, 17 respectively to obtain on the next number. So, 33 is wrong.

Question 9

190, 166, 145, 128, 112, 100, 91?

Accepted Answer

Go on subtracting 24, 21, 18, 15, 12, 9 from the numbers to get the next number. Clearly,128 is wrong.

Question 10

7, 26, 63, 124, 215, 342, (...) :

Accepted Answer

Numbers are (23 - 1), (33 - 1), (43 - 1) (53 - 1), (63 - 1) (73 - 1) etc. So, the next number is (83 - 1) = (512 - 1) = 511.

Question 11

385, 462, 572, 396, 427, 671, 264?

Accepted Answer

In each number except 427, the middle digit is sum of the other two.

Question 12

1, 8, 27, 64, 124, 216, 343?

Accepted Answer

The number are 13, 23, 33, 43 etc. So, 124 is wrong. It must have been 53 i.e., 125.

Question 13

19, 28, 39, 52, 67, 84, 102?

Accepted Answer

The pattern is x2 + 3, where x = 4, 5, 6, 7, 8, 9 etc. But 102 is out of pattern.

Question 14

4, 9, 19, 39, 79, 160, 319?

Accepted Answer

Double the number and add 1 to it, to get the next number. So, 160 is wrong.

Question 15

9, 12, 11, 14, 13, (...), 15?

Accepted Answer

Alternately, we add 3 and subtract 1.

Question 16

Complete the series 2, 5, 9, 19, 37 ....?

Accepted Answer

Second number is one more than twice the first third number is one less than twice the second, fourth number is one more than twice the third, fifth number is one less than the fourth. Therefore, the sixth number is one more than twice the fifth. So, the missing number is 75.

Question 17

71, 76, 69, 74, 67, 72, (...)?

Accepted Answer

Alternately, we add 5 and subtract 7.

Question 18

1, 2, 4, 8, 16, 32, 64, (...), 256?

Accepted Answer

Each previous number is multiplied by 2.

Question 19

10, 5, 13, 10, 16, 20, 19, (...)?

Accepted Answer

There are two series (10, 13, 16, 19) and (5, 10, 20, 40)one increasing by 3 and another multiplied by 2.

Question 20

165, 195, 255, 285, 345, (...)?

Accepted Answer

Each number is 15 multiplied by a prime number i.e., 15 x 11, 15 x 13, 15 x 17, 15 x 19, 15 x 23. So, the next number is 15 x 29 = 435.

Odd Man Out and Series Questions