I get and Error message with both of your formulas for some reason the
formulas contain invalid data

"Christobee" wrote:

I have the following PSD data. In addition to the largest number less or
equal to the lookup value I would like lookup to also give me the smallest
value larger than or equal the lookup value on another cell. I would like
Lookup to give me the Size passed by 80 percent or less which is 19 and then
80% or more which is 25.

Size (mm) % Passing
1.7 0.16
2.8 0.47
4.75 1.25
6.7 2.04
8 3.61
10 11.44
13.2 38.09
19 72.57
25 94.51