11. Выполните умножение: 1) 5 · 4/5; 2) 3 · 1/3; 3) 8/9 · 9; 4) 12/17 · 17; 5) 1/2 · 1/3; 6) 2/3 · 2/5; 7) 3/5 · 5/6; 8) 12/25 · 5/6.

1. \(5\cdot\frac45=4\).
2. \(3\cdot\frac13=1\).
3. \(\frac89\cdot9=8\).
4. \(\frac{12}{17}\cdot17=12\).
5. \(\frac12\cdot\frac13=\frac16\).
6. \(\frac23\cdot\frac25=\frac4{15}\).
7. \(\frac35\cdot\frac56=\frac12\).
8. \(\frac{12}{25}\cdot\frac56=\frac{2}{5}\).

Ответ: 1) 4; 2) 1; 3) 8; 4) 12; 5) \(\frac16\); 6) \(\frac4{15}\); 7) \(\frac12\); 8) \(\frac25\).