简便运算,越简便越好9+19+29+39+49+59+69+79+89+99
问题描述：
简便运算,越简便越好9+19+29+39+49+59+69+79+89+99
答
10*10-10
答
=10+20+30+40+50+60+70+80+90+100-10
=110*5-10
=540
10^55-10=540
答
9+19+29+39+49+59+69+79+89+99
=9*10+90*(10/2)=540
答
(10+20+30+40+50+60+70+80+90+100)-10
答
你可以发现9＋99＝19＋89＝……＝49＋59＝108
所以原式＝9+19+29+39+49+59+69+79+89+99
＝108×5
＝540