Question

1.9+19.9+199.9+1999.9+19999.9=??????????

要过程是简便运算

Answer 1

1.9+19.9+199.9+1999.9+19999.9
=（2-0.1）＋（20-0.1）＋（200-0.1）＋（2000－0.1）＋（20000－0.1）
=（2+20+200+2000+20000）-0.1*5
=22222-0.5
=22221.5

Answer 2

1.9+19.9+199.9+1999.9+19999.9
=0.9*5+1+19+199+1999+19999
=5.5+19+199+1999+19999
=(1+19)+(1+199)+(1+1999)+(1+19999)+1.5
=20+200+2000+20000+1.5
=22221.5

Answer 3

(19.9+0.1)+(19.9+0.1)+(199.9+0.1)+(+1999.9+0.1)+(19999.9+0.1)+(1.9-0.5)

Answer 4

1.9+19.9+199.9+1999.9+19999.9 =0.9*5+1+19+199+1999+19999 =5.5+19+199+1999+19999 =(1+19)+(1+199)+(1+1999)+(1+19999)+1.5 =20+200+2000+20000+1.5 =22221.5

Answer 5

1.9+19.9+199.9+1999.9+19999.9+4-4=
2+20.9+200.9+2000.9+00000.9-4=
22222+.9*4-4=22222-0.4=22221.6