101 is 10. Simple enough, but let's think this through.
We'll go one step at a time; 102 = 10 x 10 = 100
and 103 = 10 x 10 x 10 = 1,000
so 104 = 10 x 10 x 10 x 10 = 10,000
We'll go one step at a time; 102 = 10 x 10 = 100
and 103 = 10 x 10 x 10 = 1,000
so 104 = 10 x 10 x 10 x 10 = 10,000