10-10-4 opponent started hand and can't play, I play 3-2-1 . How many points do I get for the run? 4 or 7 ?
Seven. Scoring during pegging is performed after each card is played, based on the list of cards thus far. After playing the "2" you score three; after playing the ace you score an additional four. (Consider: if it were the other player that scored for the run of three, you wouldn't take those points away from them when you scored the ace!)
You would peg 8 points all at once. You would announce your play like this:
- (play the 3) "27."
- (play the 2) "29, run of 3." (Don't move the peg yet - there's more to come.)
- (play the A) "30, run of 4, and 1 for last card. 3 plus 4 plus 1 is a total of 8." (Move the peg 8 points.)