Question

Q3. Find the sum of all natural number between 100 and 500 which are divisible by 7​

Answer 1

Answer:

16,170

Step-by-step explanation:

a=105(7×15)

l=497(7×71)

d=7

l=a+(n-1)d

497=105+(n-1)7

497-105=7n-7

392+7=7n

385=7n

385/7=n

n=55

sum=n/2(2a+(n-1)d)

=55/2(2×105+(55-1)7)

=55/2(210+(54)7)

=55/2(210+378)

=55/2(588)

=55×294

=16,170