Why does SUMIF and SUMIFS not work with decimals as the condition?

Question

I'm trying to do a budget report.  The items in the budget are number 2.1, 2.2 all the way up to 2.43.  On another page I am subtracting the amounts used each month from the allotted budget for each item.  The problem that I am having is that when I put in the formula it's not subtracting right because it is ignoring the difference between 2.1 and 2.10, 2.2 and 2.20.  Here are two of the ways that I have tried but neither work
=SUMIFS(รายการจ่ายเงิน Feb. 2013 :: จำนวน,รายการจ่ายเงิน Feb. 2013 :: หมายเลขงบ,2.1)
=SUMIFS(รายการจ่ายเงิน Feb. 2013 :: จำนวน,รายการจ่ายเงิน Feb. 2013 :: หมายเลขงบ,"2.10")
=SUMIF(รายการจ่ายเงิน Jan. 2013 :: หมายเลขงบ,"2.10", รายการจ่ายเงิน Jan. 2013 :: จำนวน)
On the page with the monthlly report I have like this:
item number        description         amount
2.1                         food                5.50
2.10                     electric bill          300
on the yearly amounts page it shows the item amounts like this
2.1                     305.50
2.10                   305.50
What I need it to show is like this:
2.1                     5.50
2.10                300.00
Is there a way to make the formula reckonize the difference in the numbers and give the correct results?

Answer 1

TH,
First, you must make sure that your "Item Number" is NOT a number, but is formatted as Text.
Then, add an auxiliary column in which we make certain that the  "Item Number" will never be confused with a real number.
Finally, use the Aux column for your "Test Values" range argument in SUMIF.