Question

The sum of first 50 natural numbers which are divisible by 2 is .

• A. 650
• B. 425
• C. 325

Answer 1

The correct option is A 650

The first 50 natural numbers divisible by 2 are
2, 4, 6, 8,......, 48, 50
Their sum
= $2+4+6+8+10+......+50$
= $2\times (1+2+3+...+25)$
= $2\times \left(\frac{25(25+1)}{2}\right)$
[$\because$ Sum of first n natural numbers = $\frac{n(n+1)}{2}$]
= $2\times \left(\frac{25\times 26}{2}\right)$
= $2\times 25\times 13$
= 650
$\therefore$ The sum of first 50 natural numbers which are divisible by 2 is 650.