一定要简便算法,有一定的计算过程
1.9+19.9+199.9+1999.9+0.4=(2-0.1)+(20-0.1)+(200-0.1)+(2000-0.1)+0.4=2+20+200+2000=2222
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第1个回答 2007-06-09
1.9+19.9+199.9+1999.9+0.4=2222
第2个回答 2007-06-13
1.9+19.9+199.9+1999.9+0.4
= 1.9+19.9+199.9+1999.9+0.1+0.1+0.1+0.1
=(2-0.1)+(20-0.1)+(200-0.1)+(2000-0.1)
=2+20+200+2000+0.1+0.1+0.1+0.1-0.1-0.1-0.1-0.1
=2+20+200+2000
=2222
同类型题:
8+98+998+9998+99998+999998-12
9+99+999+9999
= 1.9+19.9+199.9+1999.9+0.1+0.1+0.1+0.1
=(2-0.1)+(20-0.1)+(200-0.1)+(2000-0.1)
=2+20+200+2000+0.1+0.1+0.1+0.1-0.1-0.1-0.1-0.1
=2+20+200+2000
=2222
同类型题:
8+98+998+9998+99998+999998-12
9+99+999+9999
第3个回答 2007-06-10
把0.4分成4个0.1分别加到前面的4个 就OK
第4个回答 推荐于2020-12-11
1.9+19.9+199.9+1999.9+0.4=?
=1.9+0.1+19.9+0.1+199.9+0.1++1999.9+0.1
=2+20+200+2000
=2222
=1.9+0.1+19.9+0.1+199.9+0.1++1999.9+0.1
=2+20+200+2000
=2222