Write $4\cdot4\cdot4$4·4·4 in exponential form.
Write $6\cdot6\cdot6\cdot6\cdot6\cdot3\cdot3\cdot3\cdot3\cdot3$6·6·6·6·6·3·3·3·3·3 in exponential form.
Simplify the following, giving your answer in exponential form: $2^2\cdot2^3$22·23.
Simplify the following, giving your answer in exponential form: $3^9\cdot3^{10}$39·310.