(41,65+8,35+8,25+21,75)x(10,55+9,45)
=(50+50)x20
=100x20
=2000
Tính nhanh:
41,65 + 8,25 + 8,35 + 9,45 . 21,75 + 10,55
= (41,65 + 8,35 ) + ( 21,75 + 8,25 ) . ( 10,55 + 9,45 )
= 50 + 30 . 20
=50 + 60
= 110
41,65 + 8,35 + 8,25 + 9,45 x 21,75 + 10,55
= (41,65 + 8,35 + 8,25 + 21,75 ) x ( 9,45 + 10,55 )
= ( 50 + 30 ) x 20
= 80 x 20
= 1600