How many different ways three two-digit numbers can be chosen so that their product ends in four or more zeros.
I could'n do more: three two-digit numbers - $XX$, $YY$, $ZZ$
- $XX$, $YY$, $ZZ$ are ending in zero -- $X0.Y0.Z0$
$X=1-9$, $Y=2,4,6,8$, $Z=5$
There are much more ways and I can't get to the solution.
Can someone give me an idea?