Spreadsheets: how do I SUM values in a column, only if the text column has a 1?

Question

Let's say I have this data

4     1
4     0
4     1
3     0
5     1

How do I write a function (using SUM or something like that) to add all the values on the left, if the values on the right are 1, or true

The total should be 13

Answer 1

Assuming columns A and B are used...

Check just for 1:

=SUMIF(B1:B5,"=1",A1:A5)

If you want to check for TRUE also:

=SUMIF(B1:B5,"=1",A1:A5) + SUMIF(B1:B5,"=TRUE",A1:A5)

Answer 2

sort by column b, then auto-sum the values you want in column a. cheap & lazy solution.