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Take any four digit number. Move the first digit to the end and move the rest along. Now add your two numbers. Did you get a multiple of 11?

How Many Miles to Go?

How many more miles must the car travel before the numbers on the milometer and the trip meter contain the same digits in the same order?

Farey Sequences

There are lots of ideas to explore in these sequences of ordered fractions.

Missing 9s

Age 11 to 14 Short Challenge Level:

Sara makes a list of the whole numbers in ascending order which do not have 9s as any of their digits.

1 is the first number on Sara's list.

What is the 300th number on Sara's list?


This problem is adapted from the World Mathematics Championships
You can find more short problems, arranged by curriculum topic, in our short problems collection.