Question

The sum of all even numbers between 21 and 51 is

• A. $518$
• B. $540$
• C. $560$
• D. $596$

Answer 1

Answer: (B)

$540$

The sum of all even numbers between $21$ and $51$

i.e. $22+24+26+28+....+50$

first term is $22$

last term is $50$

common difference is $2$

number of terms $=\frac{50-22}{2}+1=15$

$\therefore$ Sum of the terms is $=\frac{15}{2}(22+50)=15\times (11+25)=15\times 36=540$.