Evaluate the following expression: $4^7\times4^{-5}$47×4−5.

Evaluate the following expression: $8^{-10}\times8^{13}$8−10×813.

Evaluate the following expression: $5^2\times5^{-4}$52×5−4.

Simplify the following, giving your answer with a positive index: $2^3\div2^{-2}$23÷2−2

Use prime numbers, common factors and multiples, and powers (including square roots)