What is the scoring rule for a spare in bowling?

Answer 1

A strike means the next 2 balls count double, a spare means 10 points plus the next ball counts double. So a strike+spare is (10 + 10) = 20 for frame 1, and 10 more for frame 2, and the next ball counts double (and is tallied in frame 2):

frame 1: 20 (total = 20)
frame 2: 10 + next ball (total = 30+)
frame 3: next ball

A spare followed by a strike works out the same: 10 + 2*(10) = 30, and the next two balls (because of the strike) counts double. In long form, (x) + (10-x) + 2*(10).

frame 1: 20 (total = 20)
frame 2: 10 + next 2 balls (total = 30+)
frame 3: next 2 balls

A game of all strikes quickly adds to 300... if you keep doing strikes, each frame gives you 30 points because you get 10 for what you hit, plus double the next two balls (each of which gave you 10).

Answer 2

Number of pins scored on the subsequent ball + ten.

Answer 3

The next two throws count towards the frame where you got a strike.