Once you attempt the question then PrepInsta explanation will be displayed.

The number series 1, 2, 3, 4, . . . . , 35, 36.

The first term a = 1

The common difference d = 1

Total number of terms n = 36

apply the input parameter values in the formula

Sum = n/2 x (a + T_{n})

= 36/2 x (1 + 36)

= 1332/2

1 + 2 + 3 + 4 + . . . . + 35 + 36 = 666