(1+0.228-0.21)*(0.228-0.21+0.2003)-(1+0.228-0.21+0.2003)*(0.228-0.21)如何巧算?

问题描述:

(1+0.228-0.21)*(0.228-0.21+0.2003)-(1+0.228-0.21+0.2003)*(0.228-0.21)如何巧算?
写清巧算步骤.

原式=(1+0.2007)*(0.2007+0.2003)-(1+(0.2007+0.2003))*0.2007
=(0.2007+0.2003)+0.2007*(0.2007+0.2003)-0.2007-0.2007*(0.2007+0.2003)
=0.2007+0.2003-0.2007
=0.2003