Question Details

Select the number from among the given options that can replace the question mark (?) in the following series.
1, 2, 4, 8, 10, 20, ?

Options

A

40

B

24

C

22

D

42

Show Answer

Correct Answer :

Option C

22

Solution :

The correct option is 22.

To find the missing number in the sequence 1, 2, 4, 8, 10, 20, ?, let's observe the logical pattern applied to move from one term to the next:

- First step: Multiply by 2
1×2=2

- Second step: Add 2
2+2=4

- Third step: Multiply by 2
4×2=8

- Fourth step: Add 2
8+2=10

- Fifth step: Multiply by 2
10×2=20

The sequence follows an alternating pattern of multiplying by 2 and then adding 2.

Continuing this pattern, the next operation is to add 2 to the last term (20):
20+2=22

Hence, the number that replaces the question mark (?) is 22.

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