Evenly divisible means that there is no remainder.
132 is the smallest 3-digit number evenly divisible by 33.
990 is the greatest number evenly divisible by 33.
a 1 = 132, d = 33, a n = 990.
So we have to find n.
a n = a 1 + ( n - 1 ) * d
990 = 132 + ( n - 1 ) * 33
990 = 132 + 33 n - 33
990 = 99 + 33 n
33 n = 990 - 99
33 n = 891
n = 891 : 33 = 27
Answer: There are 27 3-digit numbers that are evenly divisible by 33.