All evens are divisible by 4; so "sum of even squares":
n = 70/2 = 35; f = (10-2)/2 = 4
2n(n+1)(2n+1)/3 - 2f(f+1)(2f+1)/3 = 59640 - 120 = 59520
"See" that?
Hello, rickrishav!
I hope I interpreted the problem correctly . . .
Find the sum of squares of all integers between 10 and 70 which are divisible by 4.
The integers between 10 and 70 which are multiple of 4 are:
. .
The sum of their squares is:
. .
. . . .
. . . .
. . . . .**
. . . .
. . . .
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
**
The sum of the first squares is:
. .