Question

1.怎样简便就怎样算： 42×125 473+79-63 5×999+5+99×7+7+3×9+3+9 = = = = = = = = =

42×125 473+79-63 5×999+5+99×7+7+3×9+3+9
= = =
= = =
= = =

谁知道怎么做啊~？FAST~！

Answer 1

42×125 =7x(8x125)=7x1000=7000
473+79-63 =400+73+79-63=400+79+(73-63)=489
5×999+5+99×7+7+3×9+3+9
=5x(999+1)+7x(99+1)+3x(9+1)+9
=5000+700+30+9
=5739

追问

我问问你，7×8得多少？我看你得好好背背乘法口诀了把.

追答

呃..sorry..
42×125 =5.25x(8x125)=5.25x1000=5250

Answer 2

1、42×125 =125(40+2)=5000+250=5250
2、473+79-63 =463-63+10+79=400+89=489
3、5×999+5+99×7+7+3×9+3+9
=5x(999+1)+7x(99+1)+3x(9+1)+9
=5000+700+30+9
=5739