简便运算：9.99x778+3.33x666,9991+999.1+99.91+9.9991,2007分之2006x2008
问题描述：
简便运算：9.99x778+3.33x666,9991+999.1+99.91+9.9991,2007分之2006x2008
答
9.99x778+3.33x666
=9.99*778+3.33*3*222
=9.99*(778+222)
=9.99*1000
=9990
2006/2007 *2008
=2006/2007 *(2007+1)
=2006/2007 *2007 +2006/2007
=2006+2006/2007
9991+999.1+99.91+9.9991
=9991+9+0.9991+999.1+0.9+99.01
=10000+0.9991+1000+99.01
=11000+0.99+0.0091+99.01
=11000+100+0.0091
=11100.0091