How many six-digit positive integers are there, which is evenly divisible by 4 or 9?
(If you let A be the amount of six-digit positive integers that are evenly divisible by 4 and B be the amount of six-digit positive integers that are evenly divisible by 9, so you should therefore
determine the number of elements in A ∪ B.
Remember that A and B in this case may not be disjoint sets.)
There are 900,000 six-digit numbers.How many 6x-digit positive integers are there that are evenly divisible by 4 or 9?
Every 4th number is divisible by 4: . numvbers divisible by 4.
Every 9th number is divisible by 9: . numbers divisible by 9.
But every 36th number is divisible by both 4 and 9: .