find the AP. (3,5,7,9,...20: How many three digit natural numbers are

1.	find the AP. (3,5,7,9,...20: How many three digit natural numbers are divisible by 77 (128)L tr. 11 Its 2ă¤th term rs three times Its 8th te21
Answer» 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. Hence, There are 128 three digit numbers which are divisible by 7.

find the AP. (3,5,7,9,...20: How many three digit natural numbers are divisible by 77 (128)L tr. 11 Its 2ă¤th term rs three times Its 8th te21

Answer»

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.

Hence, There are 128 three digit numbers which are divisible by 7.