Question

The hundreds digit of my number is less

than the tens digit. The ones digit is greater than
the tens digit. What could my number be?

Answer 1

Explanation:

6 7 8 is one possibility

789 is another choice.

123 even works.

So how many numbers are there like this?

You can't have 0 in the 100s place and you can't have 8 0r 9

So there are 7 numbers 1 2 3 4 5 6 7 possible choices for the hundreds.

You can't 0 in the tens place nor 1 nor 9

You can't have 0 or 1 or 2 in the units place

In all I think you could write 84 such numbers.