Question

简便计算：12.34+23.45+34.56+45.67+56.78+67.89+78.91+89.12+91.23

急！要详细点解答哟！

Answer 1

观察每个数位，都是1--9
12.34+23.45+34.56+45.67+56.78+67.89+78.91+89.12+91.23
=（1+2+3+4+。差和。。+9）虚型盯*（11.11）租祥
=45*11.11
=499.95

Answer 2

12.34=10+2+0.3+0.04
23.45=20+3+0.4+0.05
34.56=30+4+0.5+0.06
.
.
.
89.12=80+9+0.1+0.02
91.23=90+1+0.2+0.03
左右中咐伏两边相加得：
12.34+23.45+34.56+45.67+56.78+67.89+78.91+89.12+91.23
=（10+20+...+90）+（1+2+...+9）卖携+（0.1+0.2+...+0.9）简竖+（0.01+0.02+...+0.09）
=450+45+4.5+0.45
=499.95

Answer 3

12.34+23.45+34.56+45.67+56.78+67.89+78.91+89.12+91.23=(10+20+30+40+50+60+70+80+90)+(1+2+3+4+5+6+7+8+9)+(0.1+0.2+0.3+0.4+0.5+0.6+0.7+0.8+0.9)+(0.01+…宏缓…穗绝洞猜枯0.09)=450+45+4.5+0.45=499.95

Answer 4

(12.34+34.56)+(45.67+91.23)+(56.78+89.12)+(67.89+78.91)+23.45
= 499.95
=