Упр.998 ГДЗ Ткачёва 5 класс (Математика)

1) 2 · 3 1/4; 2) 6 · 1 1/8; 3) 10 · 2 2/15; 4) 4 · 3 5/6.

1) $$2 \cdot 3\frac{1}{4} = 2 \cdot \frac{13}{4} = \frac{26}{4} = \frac{13}{2} = 6\frac{1}{2}.$$

Или:

$$2 \cdot 3\frac{1}{4} = 2 \cdot \left(3+\frac{1}{4}\right) = 2 \cdot 3 + 2 \cdot \frac{1}{4} = 6 + \frac{1}{2} = 6\frac{1}{2}.$$

2) $$6 \cdot 1\frac{1}{8} = 6 \cdot \frac{9}{8} = \frac{54}{8} = \frac{27}{4} = 6\frac{3}{4}.$$

Или:

$$6 \cdot 1\frac{1}{8} = 6 \cdot \left(1+\frac{1}{8}\right) = 6 \cdot 1 + 6 \cdot \frac{1}{8} = 6 + \frac{3}{4} = 6\frac{3}{4}.$$

3) $$10 \cdot 2\frac{2}{15} = 10 \cdot \frac{32}{15} = \frac{320}{15} = \frac{64}{3} = 21\frac{1}{3}.$$

Или:

$$10 \cdot 2\frac{2}{15} = 10 \cdot \left(2+\frac{2}{15}\right) = 10 \cdot 2 + 10 \cdot \frac{2}{15} = 20 + \frac{20}{15} = 20 + \frac{4}{3} = 21\frac{1}{3}.$$

4) $$4 \cdot 3\frac{5}{6} = 4 \cdot \frac{23}{6} = \frac{92}{6} = \frac{46}{3} = 15\frac{1}{3}.$$

Или:

$$4 \cdot 3\frac{5}{6} = 4 \cdot \left(3+\frac{5}{6}\right) = 4 \cdot 3 + 4 \cdot \frac{5}{6} = 12 + \frac{20}{6} = 12 + \frac{10}{3} = 15\frac{1}{3}.$$

Ответ

1) $$6\frac{1}{2}$$; 2) $$6\frac{3}{4}$$; 3) $$21\frac{1}{3}$$; 4) $$15\frac{1}{3}$$.