1 , tính nhẩm
a)
18 x 10 = 180 82 x 100 = 8200 256 x 1000 = 256000
18 x 100 = 1800 75 x 1000 = 75000 302 x 10 = 3020
18 x 1000 = 18000 19 x 10 = 190 400 x 100 = 40000
b)
9000 : 10 = 900 6800 : 100 = 68 20020 : 10 = 2002
9000 : 100 = 90 420 : 10 = 42 200200 : 100 = 2002
9000 : 1000 = 9 2000 : 1000 = 2 2002000 : 1000 = 2002