12 + 13 + 14 + . . . 61 + 62 + 63 = ?
"sum = 12 + 13 + 14 + . . . 61 + 62 + 63 sum of n consecutive positive integers starting from 1 is given as n ( n + 1 ) / 2 sum of first 63 positive integers = 63 * 64 / 2 sum of first 11 positive integers = 11 * 12 / 2 sum = 12 + 13 + 14 + . . . 61 + 62 + 63 = 63 * 64 / 2 - 11 * 12 / 2 = 1950 answer : c"
divide(multiply(61, add(61, 12)), 13)