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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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Choose any 3 digits and make a 6 digit number by repeating the 3 digits in the same order (e.g. 594594). Explain why whatever digits you choose the number will always be divisible by 7, 11 and 13.

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Digit Sum

What is the sum of all the digits in all the integers from one to one million?

Two and Two

Age 11 to 14 Challenge Level:

Each of the different letters below stands for a different number.

How many solutions can you find to this cryptarithm?
How can you be sure you have found them all?

Can you create other similar cryptarithms?

Here are some suggestions to start you off.
     ONE + ONE = TWO

     ONE + TWO = THREE



Can you make a cryptarithm subtraction?

If you enjoyed this problem you may like to take a look at Cryptarithms

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