Hi,
Assuming data in A1,
If it's a Real Space, then the Value Must be Text, as Excel will automatically drop spaces for numbers entered, in that case, Real Space(s) with a Text Number, you just need this:
=A1+0
Otherwise, it Must be a Non-breaking Space, CHAR(160), usually happens when data is imported or downloaded, then just use this:
=SUBSTITUTE(A1,CHAR(160),"")+0