Question

what is the sum of no between 100 and 1000 which are divisible by 14

Answer 1

\[ 14*8=112\]
\[14*71=994\]
therefore there are \[64 (71-7)\] numbers between 100 and 1000 which are divisible by 14
since all these numbers are in arithmetic progression
\[\sum=64/2*(112+994)\]
\[= 35392\]