Stanislaw switala
Stanislaw switala voted up Anonymous' answer

Take a look at this to understand place value.

In this example, the "6" is the tens digit.  The "7" is the ones. 

Make sure your number is less than forty.  30, 20, etc. 

For the ones column, you need a numeral greater than 7, so..... 8 or 9!

Let's put it together.

38, 39, 28, 29, … Read more