Question

tính nhanh :

( 2015 *67 + 53 - 2005*53 +67 )

Answer 1

2015 x 67 + 53 - 2005 x 53 + 67

= 2005 x 67 + 10 x 67 + 53 - 2005 x 53 + 67

= 2005 x (67 - 53) + 67 x (10 - 1) + 53

= 2005 x 14 + 67 x 9 + 53

= 28070 + 603 + 53

= 28726

Answer 2

2015 x 67 + 53 - 2005 x 53 + 67

=2005 x 67 + 10 + 53 -2005  x 53 + 67

=2005 x  (67 -53) +67 x (10 - 1) - 53

=2005 x 14 +67 x 9 +53

=28070 + 603 + 53

=28726