Question

tính một cách hợp lí 

a: 2015 x 102

b: 998 x 45

 

Answer 1

a: 2015 x 102

= 2015 x ( 100 + 2 )

=2015 x 100 + 2015 x 2

=201500 + 4030

=205530

b: 998 x 45

=(1000 - 2 ) x 45

=1000 x 45 - 2 x 45

=45000 - 90

=44910

Answer 2

a      2015  x  102 = 2015 x (100 + 2) = 2015 x100 + 2015 x 2 = 201500 + 4030= 205530

b      998 x 45 = (1000 - 2) x 45= 45 x 1000 - 45 x 2= 45000- 90 = 45910 

Answer 3

a: 2015 x 102 = 2015 x ( 100 + 2 ) = 2015 x 100 + 2015 x 2 = 201500 + 1030 = 205530

b: 998 x 45 = ( 1000 - 2 ) x 45 = 1000 x 45 - 2 x 45 = 45000 - 90 = 44910