Divisor 19999

To determine if any number is divisible by 19999, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 7 and 2857 - then it is divisible by 19999.

The following tests must pass:

• Test if a number is divisible by 7
• The "Rick Barrett Test" for Divisibility by 2857

Easy!