First you need to work out how much string is needed -
256 pieces needed x 40cm each:
256 x 40 = 10240cm
Then, convert to metres (100cm = 1m)
10240 / 100 = 102.4m
Then, you work out how many balls are needed:
30 can fit into 102.4 3 times with .41m to spare. So, you need three balls of string, PLUS another one to cover the 41cm
So to conclude: 4 balls of string are needed.
