How to utilize date add function in Google spreadsheet?

Question

I believe the issue I am having now should be much easier in MS Excel. However, since my company uses Google Spreadsheet so I have to figure out a way.

Basically, I have

Answer 1

In a fresh spreadsheet (US locale) with 12/19/11 in A1 and DT 30 in B1 then:

=A1+right(B1,2)

in say C1 returns 1/18/12.

As a string function RIGHT returns Text but that can be coerced into a number when adding. In adding a number to dates unity is treated as one day. Within (very wide) limits, months and even years are adjusted automatically.