I am looking for a formula or function that will sum columns based on meeting
specific criteria. for example, I have an age table that with a minimum age
column then a maximum age column. I need to be able to enter an age in to a
seperate cell and have Excel sum based on the ages.

Min Max Non Tob Spouse Child EE ADD Sp ADD Ch ADD
15 24 0.46 0.69 0.535 0.679 0.266 0.14 0.072
25 29 0.53 0.78 0.45 0.679
30 34 0.65 0.97 0.49 0.679
35 39 0.9 1.46 0.675 0.679
40 44 1.24 2.19 0.97 0.679
45 49 1.99 3.48 1.52 0.679
50 54 3.05 5.87 2.365 0.679
55 59 4.98 8.28 3.63 0.679
60 64 7.95 12.37 6.205 0.679
65 69 13.95 20.68 10.595 0.679
70 74 25.17 36.36 18.88 0.679
79 50.97 65.77 37.815 0.679

Using the sample data you provided- headers in row 1 from column A ~ I
and the criterion and data in A2:I13, I got a solution by adding two
elements. The first is a total column, J, that sums your data in
advance. The next is a max age number in cell B13: it was easier to
add the max age of 999 rather than figure out a solution that left that
cell blank. By using 999 you are effectively providing an unlimited
ceiling age, but still one the formula logic can work with.

If you'll enter your target age in cell A16, enter this formula in B16:
=SUMPRODUCT(--(A16=$A$2:$A$13),--(A16<=$B$2:$B$13),$J$2:$J$13)

The formula checks your indicated age to see where it fits in the grid,
and returns the total from column J.