№ 3. Найдите произведение: 1) 3 3/8 • 7/9, 2) 4 4/7 • 2 11/12, 3) 1 11/16 • 3 5/9, 4) 1 2/13 • 1 5/8 • 1 1/7;

№ 3. Найдите произведение: 1) $$3 \frac{3}{8} \cdot \frac{7}{9} = \frac{3 \cdot 8 + 3}{8} \cdot \frac{7}{9} = \frac{27}{8} \cdot \frac{7}{9} = \frac{3 \cdot 9 \cdot 7}{8 \cdot 9} = \frac{3 \cdot 7}{8} = \frac{21}{8} = 2 \frac{5}{8}$$; 2) $$4 \frac{4}{7} \cdot 2 \frac{11}{12} = \frac{4 \cdot 7 + 4}{7} \cdot \frac{2 \cdot 12 + 11}{12} = \frac{32}{7} \cdot \frac{35}{12} = \frac{8 \cdot 4 \cdot 5 \cdot 7}{7 \cdot 3 \cdot 4} = \frac{8 \cdot 5}{3} = \frac{40}{3} = 13 \frac{1}{3}$$; 3) $$1 \frac{11}{16} \cdot 3 \frac{5}{9} = \frac{1 \cdot 16 + 11}{16} \cdot \frac{3 \cdot 9 + 5}{9} = \frac{27}{16} \cdot \frac{32}{9} = \frac{3 \cdot 9 \cdot 2 \cdot 16}{16 \cdot 9} = 3 \cdot 2 = 6$$; 4) $$1 \frac{2}{13} \cdot 1 \frac{5}{8} \cdot 1 \frac{1}{7} = \frac{1 \cdot 13 + 2}{13} \cdot \frac{1 \cdot 8 + 5}{8} \cdot \frac{1 \cdot 7 + 1}{7} = \frac{15}{13} \cdot \frac{13}{8} \cdot \frac{8}{7} = \frac{15 \cdot 13 \cdot 8}{13 \cdot 8 \cdot 7} = \frac{15}{7} = 2 \frac{1}{7}$$.