7. How many three-digit natural numbers have the product of their digits equal to 28? Write them down!
7. Since $28=2 \cdot 2 \cdot 7$, the corresponding triples of digits are:
a) 2, 2, 7;
b) $1,4,7$.
2 points

The required numbers are:
a) $227,272,722$;

2 points
b) $147,174,417,471,714,741$.

4 points

There are 9 numbers with the required properties.

2 points

TOTAL 10 POINTS