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?
When asked how old she was, the teacher replied: My age in years is not prime but odd and when reversed and added to my age you have a perfect square...
Can you work out how many of each kind of pencil this student bought?
The number 10112359550561797752808988764044943820224719 is called a 'slippy number' because, when the last digit 9 is moved to the front, the new number produced is the slippy number multiplied by 9.
Find slippy numbers ending in 4 (a small one) and in 2 and 3 (larger ones).
Explain why the slippy number ending in 9 has a unique sequence of digits; can there be more than one slippy number ending in 9?
You might like to write a short program to find other slippy numbers.