# How to divide the vibranium bar into 3 pieces? [duplicate]

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You have a bar of vibranium and the Cap needs to use it (not used up or consumed) every day but he only needs 1/7th on the first day, 2/7th on the second day and so on for 7 days.

You have a vibranium knife that can cut through it for the Cap; however the knife is only good to make 2 cuts. You are very good and can cut perfectly.

How can you cut the vibranium bar into 3 pieces so that the Cap can get the perfect amount of vibranium for each day from 1 to 7?

## marked as duplicate by klm123, wbogacz, Peter Taylor, mdc32, kaineOct 28 '14 at 14:06

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

• very close but perhaps not a dupe: puzzling.stackexchange.com/questions/2191/… – Kate Gregory Oct 27 '14 at 20:46
• Logic is the same – Huangism Oct 27 '14 at 20:47
• Logic is the same, though I find the chain link version nicer, due to it only requiring a single 'cut' - the nature of the chain link adds to it. – Tim Couwelier Oct 28 '14 at 13:01
• Wait, are we talking 7ths of the total bar here or 7ths of what remains on that day? – Weckar E. Nov 16 '16 at 9:00

## 1 Answer

Make two cuts, leaving pieces of $1/7, 2/7, 4/7$ You can select pieces to get the amount required for each day.

• Indeed, did you figure it out or seen this type before? – Huangism Oct 27 '14 at 20:43
• There is an old classic of paying for a hotel room with one link per day from a $63$ link gold chain. How few links can you cut so you can always make change. Any time I see a number $2^n-1$ I give binary a try. – Ross Millikan Oct 27 '14 at 20:45