Question

how many three digit numbers are divisible 7 solve by A P​

Answer 1

Sol:

The first three digit number which is

divisible by 7 is 105 and last three digit

number which is divisible by 7 is 994.

This is an A.P. in which a = 105, d = 7 and

l = 994.

Let the number of terms be n . Then tn =

994.

n th term of A.P = t n = a + (n - 1)d.

⇒ 994 = 105 + (n -1)7.

⇒ 889 = 7(n-1)

⇒ n -1 = 127

∴ n = 128.

∴ There are128 three digit numbers which

are divisible by 7.