Easy question for the expert. SUMIF, SUMIFS?

[NERYONEIL]

I have in column A multiple criteria
I have in column A account numbers 100, 200, 300, 400. in Column B I have dollar values
So column A Account# Coulmn B Amount $
Row 12 100 $20.00
Row 13 200 $10.00
Row 14 300 $10.00
Row 15 400 $ 90.00
Row 16 100 $10.00
Row 17 200 $15.00
Row 18 300
Row 19 400 $30.00

I want Excel to add all the 100,200,300 account # together. For this example the sum of accounts 100's, 200's and 300's will add (20+10+10+10+15) the result is 65, after that I want to Excel to add the 400's acount by itself (90+30). The result for the 400's account is 120 on this example.
What will be the formula?
Thak you!!!