Divisor 9961

To determine if any number is divisible by 9961, you must apply 2 tests successively. If all of them 'pass' - that is, if your number is divisible by 7 and 1423 - then it is divisible by 9961.

The following tests must pass:

• Test if a number is divisible by 7
• The "Mark Heron Test" for Divisibility by 1423

Easy!