Correct answer is 271
D3 = {integers between 1 to 500 divisible by 3}
D5 = {integers between 1 to 500 divisible by 5}
D7 = {integers between 1 to 500 divisible by 7}
To find number of integers between 1 to 500 that are divisible by 3 or 5 or 7 is to find
= (166 + 100 + 71) - (33 + 23 + 14) + 4
= 337 - 70 + 4 = 271