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How many three digit number are divisible by 7 |
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Answer» the first 3 digit number = 105last 3 digit no = 994105,112,119...... 994 forms an APa=105d=7an=994n=?an=a+(n-1)d994=105+(n-1)7889=7n - 7896=7nn=128hence there are 128 three digit numbers which are divisible by7 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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