How to make rows do automatic inputs?

Hello, I'm very new to Excel.

My boss wants me to fix a financial spreadsheet.


The first column, A, is the number of cases taken in each week. Each case costs $140. In the second colum, B, I want to multiply the number of cases taken in by 140 to establish the total revenue taken in.

So A = x, B = A *140

One painful way I can do this is typing out (A(same row) * 140) for each cell in B?

I really don't want to do this. How do I make each cell in the B column automatically take the input in the corresponding A column that is in it's row and multiply it by 140?

Thanks!