Question

Tính nhanh:

42 x 15 + 57 x 15 + 15

Answer 1

42 x 15 + 57 x 15 + 15

= ( 42+57+1 ) x 15

= 100              x 15

=           1500

Answer 2

= 15 ( 42+57+1) = 15 x 100 =1500

Answer 3

 =15x[42+57+1]

=15x100

1500

Answer 4

42 x 15 + 57 x 15 + 15=(42 + 57 +1) x 15= 100 x 15= 1500

Answer 5

  42 x 15 + 57 x 15 + 15

= 15 x (42 + 57 + 1)

= 15 x 100

= 1500

Answer 6

15x(42+57+1)=15x100=1500

Answer 7

42×15+57×15+15=1500