239×7.2+956×8.2 =239×7.2+956×7.2+956 =7.2×(239+956)+956 =7.2×1195+956 =7.2×1000+7.2×200-7.2×5+956 =7200+1440+956-36 =8640+920 =8640+1000-80 =9640-80 =9560
239x7.2+239x4x8.2=239x(7.2+32.8)=239x40=9560
题目应为：3.5×7.8+2.2×3.5，否则不能进行简便计算， 3.5×7.8+2.2×3.5 =3.5×(7.8+2.2) =3.5×10 =35
2.6x78+78x7.4 =78×（2.6+7.4） =78×10 =780 望采纳！
package thread.jiecheng; // 设计算法10! + 9! + 8! +...+2! + 1! public class Chengfa { public static long init = 10; public long result = 0; public static void main(String[] args) { Chengfa cf = new Chengfa(); cf.jiaCheng(init);...
295x28+295x71+295=295X(28+71+1)=295X100=29500
呃呃。。。
4.2x7.8+2.2x42 =4.2x7.8+2.2x4.2×10 =4.2x7.8+4.2×22 =4.2×（7.8+22） =4.2×29.8 =4.2×（30-0.2） =4.2×30-4.2×0.2 =126-0.84 =125.16
2.3x7.8+9.9x7.7+2.3x2.1 =2.3×（7.8+2.1）+9.9×7.7 =2.3×9.9+9.9×7.7 =（2.3+7.7）×9.9 =10×9.9 =99