Ответ:

  1. \(7.3\cdot3=21.9\).
  2. \(6.35\cdot12=6.35\cdot(10+2)=63.5+12.7=76.2\).
  3. \(17\cdot1.07=18.19\).
  4. \(0.63\cdot5=3.15\).
  5. \(80.1\cdot9=720.9\).
  6. \(55.6\cdot11=55.6\cdot(10+1)=556+55.6=611.6\).

Ответ: 1) \(21.9\); 2) \(76.2\); 3) \(18.19\); 4) \(3.15\); 5) \(720.9\); 6) \(611.6\).