Subject: geometry
Name: Sherrie
Who are you: Parent (Middle)

why is it true that a three-digit number multiplied by 7, then 11, then 13 will result in the three digits repeated twice?

Hi Sherrie.

When you multiply 7 x 11 x 13, you get 1 001. That's 1000 + 1. So when you multiply a three digit number (let's write it as "abc") by this, then abc (1000 + 1) = abc x 1000 + abc x 1 = abc 000 + abc = abcabc.

You can do something similar. Take a three digit number, multiply by 333 667, then multiply by 3.

Stephen La Rocque.>