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 Building a ruler (Posted on 2008-11-14)
I have an unmarked ruler (AD) of length 6cm. Making two marks in it, one (B) at 1cm from the left end and other (C) at 2cm from the right end, I´m able to measure any integer length from 1 to 6 cm:
```       +----+-------------+--------+
A    B             C        D```
AB = 1cm / CD = 2cm / BC = 3cm / AC = 4cm / BD = 5cm / AD = 6cm.

If I have an unmarked ruler of length 14cm, what is the minimum number of marks, and where do I have to make them, in order to be able to measure any integer length from 1 to 14cm?

 See The Solution Submitted by pcbouhid No Rating

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 16 cm | Comment 8 of 10 |
You can use five marks on a ruler of 16 cm.

2  -       5       -       5      - 1 -   2  -  1
_ _ | _ _ _ _ _ | _ _ _ _ _ | _ | _ _ | _

1 - 1 -     3  -     3   -    3    -    3   - 2
_ | _ | _ _ _ | _ _ _ | _ _ _ | _ _ _ | _ _

 Posted by monica on 2008-11-16 14:33:06

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