1999+199.9+19.99+1.999=?

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1999+199.9+19.99+1.999=?
1999+199.9+19.99+1.999=?

1999+199.9+19.99+1.999=?
1999+199.9+19.99+1.999
=1999+1+199.9+0.1+19.99+0.01+1.999+0.001-0.001-0.01-0.1-1
=2000+200+20+2-1.111
=2220.889

1999+199.9+19.99+1.999
=2000-1+200-0.1+20-0.01+2-0.001
=2000+200+20+2-(1+0.1+0.01+0.001)
=2220+2-1.111
=2220+0.889
=2220.889

2220.889

2220.899 用计算器就行了

1999+199.9+19.99+1.999
=2000-1+200-0.1+20-0.01+2-0.001
=2000+200+20+2-(1+0.1+0.01+0.001)
=2220+2-1.111
=2220+0.889
=2220.889

1999+199.9+19.99+1.999=
1999x(1+0.1+0.01+0.001)=
1999x1.111=
(2000-1)x1.111
=2222-1.111=2220.889

原式=(2000+200+20+2)-(1+0.1+0.01+0.001)=2222-1.111=2220.889

=1999+1.999+199.9+19.99=2000.999+199.9+19.99=2200.899+19.99=2220.889