Beware. The number is NOT 23.
Two and three are merely the final two digits of the number. (There are all kinds of complicated terminologies that come into play here, as per the Stackexchange reference below, but they are not necessary to the answer).
For practical purposes, the number is 0.000023. That's to say: zero point zero zero zero zero two three.
So you can say that there are three zeroes following the point before two three.
But it doesn't really make things any clearer.
For purposes of clarity I suggest you stick to zero point zero zero zero two three.
Banks and phone companies frequently arrange such digits in groups to make them clearer but (as far as I know) you can't do this with digits following the point.
If "the kid" is really smart, s/he may grasp that each zero after the point represents a further division by 10 but that's by the by.
By the way, in some countries (and currencies), a comma is used in the place of a point in accountancy.
In Portugal, where I live, nine thousand three hundred and twenty four euros and 19 cents would be shown thus: €9.324,19