2004.05×1997.05-2001.05×1999.05, how to calculate? Simple things!

2004.05× 1997.05-200 1.05× 1999.05

=(200 1.05+3)× 1997.05-200 1.05× 1999.05

= 200 1.05 x 1997.05+3x 1997.05-200 1.05 x 1999.05

= 200 1.05 x（ 1997.05- 1999.05）+3x（2000-2.95）

= 200 1.05 x-2+3x 2000-2.95 x3

=-4002. 1+6000-（3-0.05）x3

=6000-4000-2. 1-9+0. 15

=2000. 15- 1 1. 1

= 1989.05

Simple Methods of Elementary School Mathematics Induction

1, extracting common factor: This method actually uses the law of multiplication and distribution to extract the same factor, and the remaining items in the exam are often added and subtracted, and an integer will appear.

2. Excuse me: You will know the meaning of this method when you see the name. When using this method, you need to pay attention to observation and find the law.

3. Split method: Split method is to split a number into several numbers to facilitate calculation.