简便运算:1.9+19.9+199.9+1999.9+0.4=
问题描述:
简便运算:1.9+19.9+199.9+1999.9+0.4=
答
原式=(2-0.1)+(20-0.1)+(200-0.1)+(2000-0.1)+0.4 =2+20+200+2000-0.4+0.4 =2222
简便运算:1.9+19.9+199.9+1999.9+0.4=
原式=(2-0.1)+(20-0.1)+(200-0.1)+(2000-0.1)+0.4 =2+20+200+2000-0.4+0.4 =2222