All multiples of 10 have this property. n=10a becomes 100a which is 10n.
If n=10a+b with 0<b<10 and a>0, adding the zero creates
100a+b and we seek the ratio to be an integer:
solving for a gives
Since m<10 this makes for an easy search. For each m, try to find a b that makes a a whole number.
There are three solutions:
m=6, b=8, a=1
m=7, b=5, a=1
m=9, b=5, a=4
Posted by Jer
on 2016-03-21 12:30:42