Divisor 13993

To determine if any number is divisible by 13993, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 7 and 1999 - then it is divisible by 13993.

The following tests must pass:

• Test if a number is divisible by 7
• The "Stuart Sewell Test" for Divisibility by 1999

Easy!