Take any four digit number. Move the first digit to the end and move the rest along. Now add your two numbers. Did you get a multiple of 11?
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...
Suppose you had to begin the never ending task of writing out the natural numbers: 1, 2, 3, 4, 5.... and so on. What would be the 1000th digit you would write down.
Think of two whole numbers under 10, and follow the steps. I can work out both your numbers very quickly. How?
Weekly Problem 48 - 2013
What is the remainder when the number 743589 × 301647 is divided by 5?
Think of a two digit number, reverse the digits, and add the numbers together. Something special happens...
Where should you start, if you want to finish back where you started?
The number 3723 (in base 10) is written as 123 in another base. What is that base?
Visitors to Earth from the distant planet of Zub-Zorna were amazed when they found out that when the digits in this multiplication were reversed, the answer was the same! Find a way to explain why this works.
