Question 892993

I just recently started this unit and I am so confused. They said to evaluate the following and this is their answer: 

8^5 x 4^2 / 2^16 

= 2^15 x 2^4 / 2^16

= 2^3 
= 8 

My question is how did they derive at ^15 and ^4 and ^16. ? Your help is much appreciated. Thank you. 
<pre>
{{{8 = 2^3}}}, so {{{8^5}}} = {{{(2^3)^5}}}, or {{{2^(3*5)}}}, or {{{2^15}}}
{{{4 = 2^2}}}, so {{{4^2}}} = {{{(2^2)^2}}}, or {{{2^(2*2)}}}, or {{{2^4}}}
{{{2^16}}} was given.