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Modular Fractions

We only need 7 numbers for modulus (or clock) arithmetic mod 7 including working with fractions. Explore how to divide numbers and write fractions in modulus arithemtic.

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Decipher a simple code based on the rule C=7P+17 (mod 26) where C is the code for the letter P from the alphabet. Rearrange the formula and use the inverse to decipher automatically.

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Double Time

Crack this code which depends on taking pairs of letters and using two simultaneous relations and modulus arithmetic to encode the message.

Function Pyramids

Age 16 to 18 Challenge Level:

Can you find numbers for the bottom layer that give you whole numbers on the second layer?
You might like to change just one number at a time.

What is special about the numbers on the bottom layer that give whole number answers for the second layer?