Bypass Text Cells While Using Sum Feature

Is there a way to use the =SUM(--:--) feature, but to bypass any cells that contain text instead of numbers that are in the range?

I'm currently using this formula:

=SUM(N(I31)+N(L31)+N(O31)+N(R31)+N(U31)+N(X31)+N(AA31)+N(AD31))

...to only add up the number cells, as next to each cell, there is a column that has text (the reason for the "N(--:--)" is because depending on criteria, some of these cells print blank).

I just added 50 more columns that need to be added to the formula listed above and I will need to repeat this a dozen times. It will be much easier (and tidier) to be able to do something like this:

=SUM(N(I31:CL31)EXCLUDING CELLS THAT CONTAIN TEXT.