Question

how many 3 digit number are divisible by 7

Answer 1

Solution:

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.

nth term of A.P = tn = 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.

Answer 2

Hey ur solution is here:

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.

nth term of A.P = tn = 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.


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