Question

The sum of all natural numbers between 1 to
100 which are multiple of 5 is

• A. 550
• B. 495
• C. 845
• D. 950

Answer 1

The correct option is D 950

$a=5,l=95,d=5$

$l=a+(n-1)d$

$95=5+(n-1)5$

$⟹95=5n$

$⟹n=19$

Now sum of all natural no between $1$ and $5$$=\frac{n}{2}[a+l]=\frac{19}{2}[5+95]=950$