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Even Up

Consider all of the five digit numbers which we can form using only the digits 2, 4, 6 and 8. If these numbers are arranged in ascending order, what is the 512th number?

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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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Seven Up

Age 11 to 14 Challenge Level:

The number 27 is special because it is three times the sum of its digits

27 = 3 (2 + 7).

Find some two digit numbers that are SEVEN times the sum of their digits (seven-up numbers)?

Are there any three digit 'seven-up' numbers. Is it possible to find a number K such that there is a three digit number that is K times the sum of its digits (a K-up number)?