有沒有好辦法？

來源: 於 2009-12-30 08:21:09 [舊帖] [給我悄悄話] 本文已被閱讀：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!