In March we posed the problem:
"The number 3723 (in base 10) is written as 123 in another base.
What is that base?" ............ The answer to this can be found in the March problem archive.

We could have written this question as:

Find b where

So, moving on ...................

531 - 486 = 45
486 - 443 = 43

Investigate these differences when is converted to base 10 (for different values of b).

Try to explain what is happening.