Ответ:

  1. \(4\cdot2^{13}=2^2\cdot2^{13}=2^{2+13}=2^{15}\).
  2. \(625\cdot5^4=5^4\cdot5^4=5^{4+4}=5^8\).
  3. \(256\cdot4^7=4^4\cdot4^7=4^{4+7}=4^{11}\).
  4. \(3^{20}\cdot243=3^{20}\cdot3^5=3^{20+5}=3^{25}\).

Ответ: 1) \(2^{15}\); 2) \(5^8\); 3) \(4^{11}\); 4) \(3^{25}\).