999...9(1997个9)*999...9(1997个9)+1999...9(1997个9)的末尾有多少个零?

来源:学生作业帮助网 编辑:作业帮 时间:2024/04/29 03:26:02
999...9(1997个9)*999...9(1997个9)+1999...9(1997个9)的末尾有多少个零?

999...9(1997个9)*999...9(1997个9)+1999...9(1997个9)的末尾有多少个零?
999...9(1997个9)*999...9(1997个9)+1999...9(1997个9)的末尾有多少个零?

999...9(1997个9)*999...9(1997个9)+1999...9(1997个9)的末尾有多少个零?
设a=1997个9
则a+1=1后面1997个0
则原式=a²+a=a(a+1)
=1997个9×1后面1997个0
=1997个9后面1997个0

这题就等于:
999...9*(999...9+1)=999...9*100...0(1997个0)
末尾有1997个0。

1997*2个零