Question

what is the sum of the first 20 natural numbers divisible by 5 or 7?

Answer 1

it can divisible by 7
Beacouse if we add all the 20 natural no. the reasultent no. is 210 and it can divisible by 7

Answer 2

Sum of the first 20 number is
n(n+1)/2
20(20+1)/2=210
Divisible by 5
210/5=42
Divisible by 7
210/7=30