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Strange Sequence

Kids Riddles September 30, 2013

Strange Sequence

Here is a sequence of numbers:

1 11 21 1211 111221

It seems to be a strange sequence, but yet there is a system behind it…

The Question: What is the next term in this sequence?

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Solution

The system behind the sequence is that each number (except the first one of the sequence) “describes” the previous number. So 11 means one “1″, 21 means two times a “1″, 1211 means one “2″ and one “1″, and 111221 means one “1″, one “2″, and two times a “1″. The number following on 111221 is therefore 312211 (three times a “1″, two times a “2″, and one “1″).

550 total views, 2 today

Climbing Snail

Kids Riddles September 30, 2013

Climbing Snail

A snail is at the bottom of a 20 meters deep pit. Every day the snail climbs 5 meters upwards, but at night it slides 4 meters back downwards.

The Question: How many days does it take before the snail reaches the top of the pit?

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Solution:
On the first day, the snail reaches a height of 5 meters and slides down 4 meters at night, and thus ends at a height of 1 meter.
On the second day, he reaches 6 meters, but slides back to 2 meters.
On the third day, he reaches 7 meters, but slides back to 3 meters.

On the fifteenth day, he reaches 19 meters, but slides back to 15 meters.
On the sixteenth day, he reaches 20 meters, so now he is at the top of the pit!

Conclusion: The snail reaches the top of the pit on the 16th day!…

702 total views, 1 today

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