Question

8.61✖️98-61✖️8的简便方法

Answer 1

8.61✖️98-61✖️8
=8.61×（100-2）-61×8
=8.61×100-8.61×2-61×8
=861-488-17.22
=861-500+12-17.22
=361+12-17.22
=373-17.22
=373-18+0.78
=355+0.78
=355.78

Answer 2

8.61×（100-2）-61✘8
=861-17.22-488
=373-17.22
=354.78

Answer 3

8.61×98-61×8
=8.61×(100-2)-61×(10-2)
=8.61×100-8.61×2-61×10+61×2
=861-17.22-610+122
=(861-610)+122-17.22
=251+122-17.22
=373-17.22
=355.78

Answer 4

=8×98+0.61×98-0.61×800
=8×100-8×2-0.61×(700+2)
=800-16-427-1.22
=800-444.22
=355.78

Answer 5

8.61×98-61×8
=843.78-488
= 355.78