Summing values attached to each of many labels

I have seen this issue nearly fixed by using the SUMIF function, but for that it looks like you need to identify each label.

In my context, I have a similar problem, but individually setting up formulas for each label is impractical:

In column A, I have thousands of different customer account numbers. Each account has multiple transactions.
In column B, I have the dollar value for the transaction. Each row represents a separate transaction.

I want to find out the total number of dollars spent by each account for the sheet.

I need excel to find all rows with each account number (column A), and then add the values from the associated rows found in Column B.

Thanks!

Ace, Worked perfectly! Thanks for the help!