Question

Efectuati in doua moduri: a) 31*15+15*69,b) 199+23+23,c) 89*79+89*19+89*2,d)7+7*99,e) 95*101-95,f) 472*1001-472. Va rog mult ajutati-ma..

Answer 1

a) 31 x 15 + 15 x 69 = 465 + 1035 = 1500
sau 31 x 15 + 15  x 69 = 15 x (31 + 69) = 15 x 100 = 1500

b) 199 + 23 + 23 = 199 + 46 = 245
sau 199 +  23 + 23 = 222 + 23 = 245

c) 89 x 79 + 89 x 19 + 89 x 2 = 7031 + 1691 + 178 = 
sau 89 x 79 + 89 x 19 + 89 x 2 = 89 x (79 + 19 + 2) = 89 x 100 = 8900

d) 7 + 7 x 99 = 7 + 693 = 700
sau 7 + 7 x 99 = 7 x (1 + 99) = 7 x 100 = 700

e) 95 x 101 - 95 = 9595 - 95 = 9500
sau 95 x 101 - 95 = 95 x (101 - 1) = 95 x 100 = 9500

f) 472 x 1001 - 472 = 472472 - 472 = 472000
sau 472 x 1001 - 472 = 472 x (1001 - 1) = 472 x 1000 = 472000