3-digit natural numbers: 100, 101,…….. 990 and
3-digit natural numbers divisible by 7: 105, 112, 119, 126, …, 994
Here, a = 105, d= 7, l = 994
an = (l) = a + (n – 1) d
994 = 105 + (n – 1) x 7
994 – 105 = (n – 1) 7
n – 1 = 127
n = 128
Answer: There are 128 required numbers.
