Question

Number of 4-digit numbers that are less than or equal to 2800 and either divisible by 3 or by 11 , is equal to

Answer 1

The correct answer is 710.
1000−2799
Divisible by 3
1002+(n−1)3=2799
n=600
Divisible by 11
1−2799→[112799​]=[254]=254
1−999=[11999​]=90
1000−2799=254−90=164
Divisible by 33
1−2799→[332799​]=84
1−999→[33999​]=30
1000−2799→54
∴n(3)+n(11)−n(33)
600+164−54=710