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Puzzle of the week

Sunday, May 6, 2012

Two sequences of natural numbers

There are two sequences of natural numbers. The first sequence consists of all natural numbers that do not contain a particular digit, in ascending order. The second sequence consists of all the remaining natural numbers in ascending order. Every natural number occurs exactly once in exactly one of the sequences.

How many terms are there in the first sequence such that each of those terms is greater than the corresponding term at the same position in the second sequence?

[UNSOLVED]
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Random puzzle from the past

Sunday, January 8, 2012

Dropping marbles

There is a 200-storey building. You are given 5 identical glass marbles. You are allowed to drop any marble from any floor to the ground. A marble either breaks or remains intact after a drop. If it remains intact, the marble can be reused.

In the worst case, what is the minimum number of drops needed to find the highest floor in the building from which you can drop the marbles without breaking them?

[SOLVED]
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