Creating A Summary Based On Criteria

I am trying to create a summary of values based on some criteria. Here it goes, I have a list of number under a column ex 6299, 6399, 6118, 6124, 6411. I would like to create a summary table that would add all of the values associated with 6100's, 6200's etc... that are in an adjacent column. Ex. A1 is 6124 b1 is 100.00. I have tried different ways to use sumif, dsum and if but i am missing the part where the formula sees the column where the number is located then figures out if they are 6100, 6200 and so forth so it can then determine whether to add the adjacent column value. I woulld like for it to be one formula instead of two.