How many three-digit numbers are divisible by 7?
Answer: A
The three-digit numbers are from 100 to 999. First three-digit number divisible by 7 is 105. Last is 994. This is an A.P. with \(a=105, d=7, a_n=994\). We use \(a_n = a+(n-1)d\). \(994 = 105+(n-1)7 \Rightarrow 889 = (n-1)7 \Rightarrow n-1 = 127 \Rightarrow n=128\). There are 128 such numbers.