1999*3.14+199.9*3.14+19.99*3.14=?怎么样简便运算?写出主要过程.
问题描述:
1999*3.14+199.9*3.14+19.99*3.14=?
怎么样简便运算?写出主要过程.
答
1999*3.14+199.9*3.14+19.99*3.14
=3.14*(1999+199.9+19.99)
=3.14*(1999+1+199.9+0.1+19.99+0.01-1.11)
=3.14*(2000+200+20-1.11)
=3.14*2220-3.14*1.11
答
原式=(2000-1)*3.14+(200-0.1)*3.14+(20-0.01)*3.14
=6276.86+627.686+62.7686
=6967.3146