Use the formula S = n (n + 1)2 to find the sum of 1 + 2 + 3 + ... + 385.=
.
Use the formula S = n2 to find the sum of 1 + 3 + 5 + ... + 915. =
(Hint: To find n, add 1 to the last term and divide by 2.)
Sum 1 + 2 + 3 + ....+ 385 = [ 385] [386] / 2 = 74305
Sum of first n odds = [ ( odd integer + 1 ) / 2 ] ^2 = ( [ 915 + 1 ] .2 )^2 =
( 916 / 2)^2 = 458^2 = 209764