Need to write IF formula in shorthand

I have two columns of data, one column represents transactions and the other are dates in the month which are entered as 1 or 2 or 3 etc. From the numbers I wanted to tabulate all the transactions against cells with number 1 and 2 and 3 etc etc up to 31 days. This calculates the total of transactions for each day. The number of transactions per day is random and can be none or up to 12 or so. This is a sample the formula I used:

=IF((A13=1),(B13))+IF((A14=1),(B14))+IF((A15=1),(B15))+IF((A16=1),(B16))

then for No. 2s =IF((A13=2),(B13))+IF((A14=2),(B14))+IF((A15=2) etc etc

Sometimes there may be no entries for the first few days of the month. Other days may have no data.

This formula works but as you continue producing code for consecutive days you need more and more repetitions of the formula and eventually my Excel gave a message "Formula Too Long".

I would be grateful if anybody might suggest a shorthand way of writing the formula as I have researched it on the web and tried everything without success.

Thank you for any help or suggestions.

MikeX

p.s. I need to use a range of 500 rows for this formula as by day 31 the transactions may extend as a list to 300 or more cells. Although early in the month the number of rows used would be limited by end of month a longer list would have been generated, hence the need to cover a long range.

Any help most appreciated.

MikeX

NBVC

Absolutely brilliant Sir and it works perfectly. I cannot believe how quickly you responded. Thank you so much. I will be staying with this forum and maybe I will learn something.

MikeX