You will need

Round Neck Cardigan
20in Chest - 3 Balls
22in Chest - 3 Balls
24in Chest - 4 Balls
26in Chest - 4 Balls
28in Chest - 5 Balls
30in Chest - 5 Balls

V Neck Cardigan
20in Chest - 3 Balls
22in Chest - 3 Balls
24in Chest - 4 Balls
26in Chest - 4 Balls
28in Chest - 5 Balls
30in Chest - 5 Balls

5mm and 6mm Needles
3 (4 : 5 : 5 : 5 : 6) Buttons for Round Neck Cardigan
2 (3 : 3 : 4 : 4 : 5) Buttons for V Neck Cardigan