Heh, I assumed there was some native expression like "NumberVariable = ToNumber("99") but Construct 2 is smarter than I thought.
I can simply assign the string to a number variable and it converts it.
It converts a straight number like "99" and even a combination like "99apples". It knows to just capture the 99.
It doesn't like this obviously "apples" or "apples99"
And if you give it something like "99apples100", then it just picks the "99".
Lesson learned!