problem

### More Secret Transmissions

In 'Secret Transmissions', Agent X could send four-digit codes error free. Can you devise an error-correcting system for codes with more than four digits?

problem
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More Secret Transmissions

In 'Secret Transmissions', Agent X could send four-digit codes error free. Can you devise an error-correcting system for codes with more than four digits?

problem
###
Secret Transmissions

How can Agent X transmit data on a faulty line and be sure that her message will get through?

problem
###
Balance Power

Using balancing scales what is the least number of weights needed
to weigh all integer masses from 1 to 1000? Placing some of the
weights in the same pan as the object how many are needed?

problem
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Alien Counting

Investigate the different ways these aliens count in this
challenge. You could start by thinking about how each of them would
write our number 7.

problem
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Guesswork

Ask a friend to choose a number between 1 and 63. By identifying which of the six cards contains the number they are thinking of it is easy to tell them what the number is.

problem
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Knapsack

You have worked out a secret code with a friend. Every letter in the alphabet can be represented by a binary value.

problem
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Composite Notions

A composite number is one that is neither prime nor 1. Show that
10201 is composite in any base.

problem
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Phew I'm Factored

Explore the factors of the numbers which are written as 10101 in
different number bases. Prove that the numbers 10201, 11011 and
10101 are composite in any base.

problem
###
Back to the Planet of Vuvv

There are two forms of counting on Vuvv - Zios count in base 3 and
Zepts count in base 7. One day four of these creatures, two Zios
and two Zepts, sat on the summit of a hill to count the legs of the
creatures they could see. The creature looking to the West wrote
122. The creature looking to the East wrote 22. The creature
looking to the South wrote 101. The creature looking to the North
wrote 41. In which direction are the 2 Zios looking and in which
directions are the 2 Zepts looking?