有没有好办法？

来源: 于 2009-12-30 08:21:09 [旧帖] [给我悄悄话] 本文已被阅读：次

The sum of the number in each line, column and diagonal in the 3x3 "magic
square" bellow is always constant. Only two numbers are visible.
Which number is missing in field a?

a x x
x x 47
x 63 x

Thanks!