Question

In the following number series only one number is wrong. Find out that number:

1, 2, 6,15, 20, 30, 42 

Options

• 30

• 15

• 6

• 1

Answer 1

15 

Explanation:

The pattern of the series is as follows:

1² + 0 = 1

1² + 1 = 2

2² + 2 = 6

3² + 3 = 12

4² + 4 = 20

5² + 5 = 30

6² + 6 = 42

So, the incorrect number is 15.