=SUMPRODUCT(--(A1:A24="Tom"),--(B1:B24="May"),--(C1:C24))
First Array (Names) & Second Array (Months) and Third Array is numbers to
sum up.

Now I can easily add up all the expenses for each employee for the month, as
the employee and month are likely to have multiple entries, on more than one
row for instance.

But Now I want to do it for the quarter. So If it's X Employee and either
Jan, Feb, Mar, or April, Sum Amounts.....

I could probably write a really long formula to do that... is there a good
and concise way to do that... so someone after me could actually tell what
I'm doing with this formula.