Every other number from a list of consecutive natural numbers (2 4 6 8...) is even, and is therefore divisible by 2.

Every third number from a list of consecutive natural numbers (3 6 9 12...) is a multiple of 3, and is therefore divisible by 3.

So every combination of three consecutive natural numbers will include one even number and one multiple of three, and the product will

therefore be divisible by 2 and 3, and also by the product of 2 and 3 that is 6 (2*3=6).