Question

s2=33+34+......+72 =​

Answer 1

Gauss:

1 + 2 + 3 + ... + n = n ( n + 1 ) : 2

s2 = 33 + 34 + ... + 72 = 72 × ( 72 + 1 ) : 2

s2 = 72 × 73 : 2

s2 = 5 256 : 2

s2 = 2 628