50 за решение! 34*67= 56*8*657= 98*45= 78*534-65=

34 * 67 = 30*60 + 4 * 60 + 30 *7 + 4*7 = 1800 + 240 + 210 + 28 = 2278

56 * 8 * 657 = 448 * 657= (50*8 + 6*8)* 657 = (400+48)* 657 =
= 448 * 657 = (400* 600 + 40*600 + 8*600) + (40*600 +40*50+40*7)+
(8 *600 + 8*50+8*7) = 294336

98 * 45 = 90*40 + 8*40 + 90 *5 + 8*5 = 3600 + 320 + 450 + 40 = 4410

78*534 - 65 = (70 *500 + 70*30 + 70*4) + (8*500 + 8*30 + 8*4) - 65 =
= 35000+2100+280+ 4000+ 240 +32-65 = 41652 - 65 = 41587

Решение столбиком по действиям