Question

What is the sum of the first 21 even numbers? FAST!!!

Answer 1

462

Explanation:

Sum = n/2 x (a + Tn)

= 21/2 x (2 + 42)

= (21 x 44)/ 2

= 924/2

2 + 4 + 6 + 8 + 10 + 12 + . . . . + 42 = 462