n the following number series, a wrong number is given. Find out the wrong number.8, 15, 31, 57, 93, 143, 20

The series is increasing and seems to be increasing by an increasing amount each time. Let's look at the differences between each pair of numbers:

15 - 8 = 7 31 - 15 = 16 57 - 31 = 26 93 - 57 = 36 143 - 93 = 50 20 - 143 = -123

The differences between the numbers are not consistent, but they seem to be increasing by 9 each time, except for the last two differences. If we continue the pattern of increasing the difference by 9, the difference between 93 and the next number should be 45 (36 + 9), not 50.

So, the next number after 93 should be 138 (93 + 45), not 143. Therefore, 143 is the wrong number in the series.