Question

Find the natural numbers between 101 and 999 which are divisible by both 2 and 5.

Answer 1

Heya!!

If a no is divisible by both 2 & 5, then it is multiple of 10.

Hence AP is lyk : 10,20,30,......990..

Here first term(a) = 10,
last term(a n) = 990
To find n :

Since a n = a + (n-1)d

Here d = 20-10 = 10

=) 990 = 10 + (n-1)10

=) 990-10 = (n-1)10

=) 980 = (n-1)10

=) 980/10 = n-1

=) 98 = n-1

=) 98 + 1 = n

=) 99 = n

Hence total numbers btw 101 and 999 which are divisible by both 2 and 5 = 99.

Hope it helps uh!!