Question

Find the sum of all those integers between 100 and 800 each of which on division by 16 leaves the remainder 7.

Answer 1

AP->103,119,135...791
`a_n=a+(n-1)d`
`791=103+(n-1)16`
`688=(n-1)16`
`43-n-1`
`n=44`
`S_n=n/2[a+l]`
`=44/2[103+791]`
`=22[894]`
`=19668`.