Выполни умножения 15*4; 13*6; 17*2; 21*3; 11*8; 14*7

1) 15 * 4 = (10 + 5) * 4 = 10 * 4 + 5 * 4 = 40 + 5 * 4 = 40 + 20 = 60;

2) 13 * 6 = (10 + 3) * 6 = 10 * 6 + 3 * 6 = 60 + 3 * 6 = 60 + 18 = 60 + 10 + 8 = 70 + 8 = 78;

3) 17 * 2 = (10 + 7) * 2 = 10 * 2 + 7 * 2 = 20 + 7 * 2 = 20 + 14 = 20 + 10 + 4 = 30 + 4 = 34;

4) 21 * 3 = (20 + 1) * 3 = 20 * 3 + 1 * 3 = 60 + 1 * 3 = 60 + 3 = 63;

5) 11 * 8 = (10 + 1) * 8 = 10 * 8 + 1 * 8 = 80 + 1 * 8 = 80 + 8 = 88;

6) 14 * 7 = (10 + 4) * 7 = 10 * 7 + 4 * 7 = 70 + 4 * 7 = 70 + 28 = 70 + 20 + 8 = 90 + 8 = 98.