Scoring the game incorrectly

Question

I did not see my opponents double score and only wrote down 5 points instead of 10. My opponent knew but said nothing and at end of game when I won, he protested because of a bad score. Also he made a word that I was thinking about challenging and forgot to write that score down. Both mistakes would not of won the game for him since I was over 100 points ahead. He said that I couldn't win and had to forfeit because I made a mistake in scoring. Does anyone know the rules.

Answer 1

I'm not sure which game you mean, so I don't know which rules apply.  If we knew the name of the game it would be easier to answer.

If the game is Scrabble, and if it is a friendly game, for sure you would not forfeit the game.  You'd just make the adjustment.  In any tournament game, the mistake could not have occurred.  And he is the one who is wrong if he was aware of the error and did not say so.  

Answer 2

Sounds like he's a bit of a sore loser if the miscalculations wouldn't have won him the game anyway. According to WORLD ENGLISH-language SCRABBLE PLAYERS ASSOCIATION rules a challenge of the score has to be made during the game itself, not afterwards. (see section 4.1.e) so I'd say he's wrong telling you you should forfeit.

Anyway, I'd offer a rematch and let him keep the score. Keep an eye on him though :-)