19. If n is a positive integer, then n(n+1)(n+2)is
Sol:
n(n+1(n+2) will be even, whether n is even or odd because either (n+1) or (n+2) will be even.
n(n+1)(n+2) will be divisible by 3, whether n is even or odd, because either of n or n+1 or n+2 will be a divisor of 3.
n(n+1) (n+2) will be divisible by 4 whenever n is even because either n or n+2 will be a divisor of 4.