How it works
Checked in this game's physics, not reviewed by a coach. Three published sources teach this same formula, under the names KOBA, Kobayashi and Zigzag.
A zigzag across the table: the cue ball drives the red, near a long rail, along that rail, then crosses the table, comes back and crosses again to the target by the near rail. The side decides how far along the table it travels: Effect = D + 2 − O.
D is how far the target stands from the red along the long rail — negative when it lies the other way. O is the cue ball's offset: where its line through the red's side meets the near rail, counted from straight across. An offset of 2 with the target level with the red plays no side.
Reading the numbers
Start On the near long rail's diamonds: where the cue ball's line to the red's side, carried on, meets the rail. O is this number minus the red's.
Aim On the far long rail: the diamond the red stands at.
Arrival On the near long rail: the diamond the target ball stands at. D is the red's number minus this one.
Step by step
- Read the red's diamond on the far rail and the target's on the near rail: D = red − target, negative when the target is on the other side.
- Read the start where the cue ball's line meets the near rail: O = start − red.
- Effect = D + 2 − O. Target 2 diamonds on with an offset of 2: (2 + 2) − 2 = 2 tips of running side. Target 2 diamonds the other way: (−2 + 2) − 2 = −2, two tips of reverse side.
- Add the table correction, then strike hard: a high tip, follow, a long stroke.
The stroke
Hard and long: a high tip, follow through, and the side the formula gives — running for a positive answer, reverse for a negative one.