Post bank transactions to bank Recon as individual amounts instead of sums

I'm trying to find a quick and easy way to get our bank rec filled in. We get the transactions from the bank with columns for the date, amount, and a location identifier. In the past the transactions were hand keyed into the recon, but that was when we had a lot less locations and would take way too long now. I want to take the entire month's (or at least a week) worth of information and get it onto the recon all at once. However, I need the transactions entered as individual transactions that are added together. For instance if location A had three deposits; 100.00, 200.00, 300.00, I need it to show up in the cell as =100+200+300 instead of just 600.00.

I have a large spreadsheet that is just heavy with formulas like this:
=IFERROR(INDEX(BlkRng, SMALL(INDEX(($A9=BlkSer)*(MATCH(ROW(BlkSer), ROW(BlkSer),0))+($A9<>BlkSer)*1048577, 0, 0),ROW($A$1)),COLUMN($A$1))," ")

Given a single date worth of info, and the help of a couple other formulas, that spreadsheet can output what I need:
=1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16

That spreadsheet works, but I can only input one date of information and its slow to process just that data. I have started using Sumifs just to get all the information at least filled in, but it's not really what I would like to have.
I've attached an example of what I'm doing. I think this could be done with VBA, but it's beyond my abilities. I can understand and alter some VBA, but I'm not very good at starting from scratch.
Thanks in advance for your help!

Could you send a sample of the input

I put everything on the example sheet attached. Input examples are in J1:L28.

It was done in about as much time as it took me to click the button! I'm sure it'll be a little slower once I try it with real data, but even then it will be an improvement on what we do currently. Thank you for your help!

You are AWESOME!
I had to add a some code at the end to put an equal sign in front of the results, but this works great!
I fed it 50,000+ transactions with 200+ locations and it took <5 seconds.
Thank you!