8. Three consecutive positive integers less than 20 are, in ascending order, prime, even and triangular. What is the product of these three integers?
A 6
B 60
С 990
D 1786
E 2730
8. E First note that the triangular numbers less than 20 are $1,3,6,10,15$. As we are looking for a sequence of consecutive integers which are respectively prime, even, and triangular, the required
triangular number is odd. So it is 3 or 15 . It is not 3 as 1 is not prime, but it is 15 as 13 is prime. So the required product $=13 \times 14 \times 15=2730$.