简便运算（比如2（1/2）读作二又二分之一）11×91+209×
11×91+209×998+627 998×563+8126
11×91+209×998+627 =10×91+91+209×1000-209×2+627 =910+209000+91-418+627 =210210 998×563+8126 =1000×563-563-563+8126 =1000×563+7000 =1000×(563+7) =570000