My colleague probably has left work now, he is no longer responding. He gave me this puzzle and asked me to fill in the '?':
4 | 5 | 8 | 3 | 7
6 | 3 | 7 | 5 | 6
8 | 2 | 3 | 7 | 9
2 | 3 | 5 | 1 | 8
1 | 9 | 2 | 1 | 7
9 | 4 | 6 | 8 | ?
I tried seeing patterns from different angles. After a while I asked for a clue:
Him: It's a mathematical puzzle
Me: Are you supposed to insert operators(-+*/)
Him: Yes
Him: I can tell you it is a Mensa creation
I don't have the answer for this puzzle. But I suspect I'll get it next week if you don't get there first! I am out of ideas