Multiplied averaging works like this:

Let's suppose you have 4 grades, 3 homework and 1 test (H90 H96 H94 T86). Multiplied averaging where the test has three times the weight of a homework grade would simply average it like this (H90+H96+H94+T86+T86+T86)/6. In other words, the test is entered three times and then a straight, unweighted average is computed.