What is the most efficient method for simplifying the expression x^8/x^3

Since x^8=x*x*x*x*x*x*x*x and x^3=x*x*x , then
x^8/x^3=(x*x*x*x*x*x*x*x)/x*x*x=x^5

However, expansion is not efficient, especially for large exponents.

What can you do with the exponents to avoid expansion?

You can subtract the exponents when dividing powers with the same base. So, x^8/x^3 = x^(8-3) = x^5.