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.