It's easy.
1 ball, all down = a strike. 10 pins plus the count on the next 2 balls.
2 balls, all down = a spare. 10 pins plus the count on the next ball.
3 balls. Record the total pins knocked down.
There is strategy in this game, since the pins are left on the deck until either all are knocked down or 3 turns have been taken. You can use the fallen pins on the deck to hit them into the remaining pins standing.
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Storm - Shift 16# Medium Length
Legends - Conqueror 16# Heavy arc
Brunswick - Scorchin Inferno 16#, Med-Heavy oil
Legends - Terminator 16# Heavy length
Legends - BigRBang 16# Medium Arc