The first 3 digit number that is divisible by 7 is 105 and the last 3 digit number is divisible by 7 is 994.

To find out all the numbers falling between 105 and 994, that are divisible by 7 we will apply the formula
AP= tn= a+ (n-1) d

Where a= 105, d=7, tn =994

Let number of terms= n, thus

994= 105+ (n-1) 7

994-105=7n-7

889=7n-7

n-1= 889/7

n-1= 127

n=127+1

n= 128

Therefore there are 128 three digit numbers that are divisible by 7.