counting multiple conditions

[Shasta]

Hello everyone! I have read through a few post regarding this matter and
have tried to get my formulas to work based on previous suggestions to like
minded topics, but sadly have had no success. Here's my delima:

I have a spreadsheet where i need to count for 1 when two varibles are
present in different cells. For example:
a b
1 RD 1
2 RD 1
3 RD 1
4 RD 2
5 QA 2

I want to only count when the data in cell A1 is RD AND the data in cell B1
is 1. So whatever formula i enter should give me a count of 3.

I have tried sumproducts, but that does not seem to work. Can anyone please
help me with this, and explain why the formula works like it does. Although
at this point i would happily settle for just a formula that works without an
explanation.

Thanks in advance.

 

[Bob Phillips]

=SUMPRODUCT(--(A1:A100="RD"),--(B1:B100=1))

 

[Alan]

=SUMPRODUCT((A1:A100="RD")*(B1:B100=1))
or
=SUMPRODUCT(--(A1:A100="RD"),--(B1:B100=1))
Regards,