Question

2004.05×1997.05－2001.05×1999.05，怎么算？要简便的！

Answer 1

如下：

2004.05×1997.05－2001.05×1999.05

=(2001.05+3)×1997.05－2001.05×1999.05

=2001.05x1997.05+3x1997.05-2001.05x1999.05

=2001.05x(1997.05-1999.05)+3x(2000-2.95)

=2001.05x-2+3x2000-2.95x3

=-4002.1+6000-(3-0.05)x3

=6000-4000-2.1-9+0.15

=2000.15-11.1

=1989.05

小学数学简便方法归纳

1、提取公因式：这个方法实际上是运用了乘法分配律，将相同因数提取出来，考试中往往剩下的项相加减，会出现一个整数。

2、借来借去法：看到名字，就知道这个方法的含义。用此方法时，需要注意观察，发现规律。

3、拆分法：拆分法就是为了方便计算把一个数拆成几个数。

Answer 2

2004.05×1997.05－2001.05×1999.05
=(2001.05+3)×1997.05－2001.05×1999.05
=2001.05x1997.05+3x1997.05-2001.05x1999.05
=2001.05x(1997.05-1999.05)+3x(2000-2.95)
=2001.05x-2+3x2000-2.95x3
=-4002.1+6000-(3-0.05)x3
=6000-4000-2.1-9+0.15
=2000.15-11.1
=1989.05

Answer 3

2004.05×1997.05-2001.05×（1997.05+2）

=2004.05×1997.05-2001.05×1997.05-2001.05×2

=3×1997.05-2001.05×2

=3×1997.05-2001.05×（3-1）

=3×1997.05-2001.05×3+2001.05

=3×（1997.05-2001.05）+2001.05

=-12+2001.05 = 1989.05

Answer 4

2004.05×1997.05－2001.05×1999.05
=2004.05*1999.05 - 2004.05*2 - 2001.05*1999.05
=(2004-2001)*1999.05 - 2004.05*2
=3*1999.05 - 2*2004.05
=3*1999 + 3*0.05 - 2*2000 -2*4.05
=3*2000 - 3 + 0.15 - 2*2000 -8.10
=2000 - 3 + 0.15 - 8.10
=2000 +0.15 - 11.10
=1989.05

Answer 5

2004.05×1997.05－2001.05×1999.05
=(2001.05+3)×1997.05－2001.05×1999.05
=2001.05x1997.05+3x1997.05-2001.05x1999.05
=2001.05x(1997.05-1999.05)+3x(2000-2.95)
=2001.05x-2+3x2000-2.95x3
=-4002.1+6000-(3-0.05)x3
=6000-4000-2.1-9+0.15
=2000.15-11.1
=1989.05