25 into 21 best min fragment found: 7
  Cut up 25 sticks of length 21 like this:
    6 x (10 + 11)
    6 x (9 + 12)
    6 x (8 + 13)
    7 x (7 + 7 + 7)
  Reassemble as 21 sticks of length 25 like this:
    6 x (12 + 13)
    3 x (7 + 9 + 9)
    6 x (7 + 8 + 10)
    6 x (7 + 7 + 11)