Number bases

problem
More secret transmissions

Age

16 to 18

Challenge level

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

Age

14 to 16

Challenge level

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

Age

7 to 11

Challenge level

How would you count the number of fingers in these pictures?
problem
Balance power

Age

11 to 18

Challenge level

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
Alien counting

Age

7 to 11

Challenge level

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
Guesswork

Age

14 to 16

Challenge level

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
Knapsack

Age

14 to 16

Challenge level

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

Age

14 to 16

Challenge level

A composite number is one that is neither prime nor 1. Show that 10201 is composite in any base.
problem
Phew I'm factored

Age

14 to 16

Challenge level

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

Age

11 to 14

Challenge level

There are two forms of counting on Vuvv - Zios count in base 3 and Zepts count in base 7. Can you work out in which direction the Zios and Zepts were looking, based on the information you're given?