By instinct most new bowlers looks at the target pin when attempting a spare. There is a better and more scientific way !
3-6-9 System
This system assumes that once you have found your strike position, remember it . For a right-hander, the strike position simply means the position ( say the centre dot at the approach) which you start with & bowl over the the target arrow (typically the 2nd arrow from the right gutter) to roll your ball into the 1-3 pocket.
The 3-6-9 sparing system assumes that you will fix your target arrow and move your starting position left to spare pins on the right or move right to spare pins on the left
To spare :
Pin 3 & 9 - move 3 boards left of your strike position & bowl over the target arrow
Pin 6 - move 6 boards left of your strike position & bowl over the target arrow
Pin 10 - move 12 boards left of your strike position & bowl over the target arrow+ 5 boards to the left
Pin 2 & 8 - move 3 boards right of your strike position & bowl over the target arrow
Pin 4 - move 6 boards right of your strike position & bowl over the target arrow
Pin 7 - move 9 boards right of your strike position & bowl over the target arrow
2-4-6 System
This system also assumes that once you have found your strike position, remember it . For the right hander, the strike position simply means the position ( say the centre dot at the approach) which you start with & bowl over the the target board (typically the 10th board from the right gutter) to roll your ball into the 1-3 pocket
The 2-4-6 sparing system assumes that you will fix your standing position and shift your target board left to spare pins on the left or shift your tarfet board right to spare pins on the right.
To spare :
Pin 3 & 9 - stand at the strike position & bowl over the target board-2 (i.e 8th board from right gutter)
Pin 6 - stand at the strike position & bowl over the target board-4 (i.e 6th board)
Pin 10 - stand at the strike position & bowl over the target board-6 (i.e 6th board)
Pin 2 & 8 - stand at the strike position & bowl over the target board+2 (i.e 12th board from right gutter)
Pin 6 - stand at the strike position & bowl over the target board+4 (i.e 14th board)
Pin 10 - stand at the strike position & bowl over the target board+6 (i.e 16th board)