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!
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.
Eminit
Age 11 to 14 Challenge Level
The number 8888...88M9999...99 is divisible by 7 and it starts
with the digit 8 repeated 50 times and ends with the digit 9
repeated 50 times. What is the value of the digit M?