1kg box = 220 pieces per box
220 pieces makes 42-44 bomboniere with 5 pieces in each
If you need to do 180 bomboniere you would do the following to work out how many kilos you need exactly.
180 (bomboniere) x 5 (pieces of confetti) = 900 (pieces total)
900 / 220 (the amount in each box) = 4.09 boxes
Round this off to the next whole number, which is 5.
You now know you will need 5 boxes to complete your bomboniere.