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Adding All Nine

Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some other possibilities for yourself!

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Double Digit

Choose two digits and arrange them to make two double-digit numbers. Now add your double-digit numbers. Now add your single digit numbers. Divide your double-digit answer by your single-digit answer. Try lots of examples. What happens? Can you explain it?

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Legs Eleven

Take any four digit number. Move the first digit to the 'back of the queue' and move the rest along. Now add your two numbers. What properties do your answers always have?

Weekly Problem 25 - 2009

Stage: 3 Short Challenge Level: Challenge Level:1
5.

The only way to get 87 is to get 13 questions correct and 2 wrong, leaving 5 questions unattempted.

This problem is taken from the UKMT Mathematical Challenges.

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