countNumberUsage-- counts "½" as two numbers

Questions
1

It looks like countNumberUsage counts fractions, like ½, as two numbers. Not sure. I am wanting students to enter “½” and not an expression equivalent and not sure how to check for that. Of course they could enter as a decimal-- countNumberUsage seems to count 0.5 as one number.

Ideas?

2

It looks like countNumberUsage counts fractions, like ½, as two numbers.

Yes, it does, so:

...input.numericValue=0.5 and countNumberUsage(input.latex,1)=1 
and countNumberUsage(input.latex,2)=1

If your fractions are dynamic, you can use variables for the second parameter.