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 tha

Answer 1

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