Google Spreadsheet: Adding formulas to Google Forms responses rows

Question

I have a sheet with form response data in several columns, say A:G. Some of the data are numerical and I'd like to have some calculations done on them, e.g. in columns H through J. I have already found out any stretched formulas get wiped out as new lines from the form get pulled in.

So I created a new sheet, imported the data using arrayformula, but still, I don't know how to have a formula for every row in columns H:J (except the header). I can only stretch the formula within a fixed number of rows, but don't know how to make it autoadjust to newly incoming data.

I wondered if I could use a script that would be triggered with the form being submitted, adding the formulas to the new lines, but that's rather inelegant.

Sample spreadsheet: Sheet1 contains form data, Sheet2 imports them using arrayformula.

Answer 1

If you add the following formula in cell D2:

=ARRAYFORMULA(FILTER(C2:C;C2:C<>"")*1.2)

then it will take on the complete column, via the array. The FILTER function, is to make sure no empty cells are taken into account.

I've added the result into the file you shared with us.

Answer 2

A shorter version of the formula in the answer by Jacob Jan Tuinstra

=FILTER(C2:C*1.2;C2:C<>"")

FILTER is a function that returns an array so, if the operations are done in the first argument, the outer ARRAYFORMULA function it isn't required.