12345*98765-12344*98766的解法1
问题描述：
12345*98765-12344*98766的解法
1
答
a*b-(a-1)*(b+1)=ab-ab-a+b+1=-a+b+1=86421
答
12345*98765-12344*98766
=12345*98765-(12345-1)*(98765+1)
=12345*98765-12345*98765-12345+98765-1
=98765-12346
= 86419