Reply to comment

Multiple of 9

The difference between 2 numbers wil the same digits will always be a multiple of 9.
Consider a 2 digit number as 10x + y. Transpose the digits; 10y + x. (10x + y) - (10y + x) = 9x - 9y.


  • Web page addresses and e-mail addresses turn into links automatically.
  • Allowed HTML tags: <a> <em> <strong> <cite> <code> <ul> <ol> <li> <dl> <dt> <dd>
  • Lines and paragraphs break automatically.

More information about formatting options

To prevent automated spam submissions leave this field empty.
By submitting this form, you accept the Mollom privacy policy.