Players take turns placing numbers from 1-9 on the grid. Each digit can only be used three times. Avoid making three-digit prime numbers in any direction!
Get Ready
Game Instructions
- Objective: Avoid creating three-digit prime numbers while placing digits on the grid.
- Turn Order: Players take turns selecting a digit (1-9) and placing it on the grid.
- Digit Limitation: Each digit (1-9) can only be used three times in total.
- Prime Numbers: If a player's move creates a three-digit prime number in any direction (horizontal, vertical, or diagonal), their opponent scores a point.
- Winning: The game ends when the grid is full or no more moves are possible. The player with the highest score wins!
Challenge Instructions
- Objective: Avoid creating three-digit prime numbers while placing digits on the grid.
- Digit Limitation: Each digit (1-9) can only be used three times in total.
- Trophy: If you manage to fill the whole grid without making any three-digit primes than a virtual trophy is available.
Examples of 3-digit primes: 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, etc.
Divisibility Tests:
A number is divisible by 2 if its last digit is even (0,2,4,6 or 8)
A number is divisible by 3 if the sum of its digits is divisible by 3.
A number is divisible by 4 if the number's last two digits are divisible by 4.
A number is divisible by 5 if its last digit is a 0 or 5.
A number is divisible by 6 if it is divisible by 2 and 3 (see rules above).
A number is divisible by 7 if 5 times the last digit added to the number made from the other digits is divisible by 7.
A number is divisible by 8 if the last three digits form a number that is divisible 8.
A number is divisible by 9 if the sum of the digits is divisible by 9.
A number is divisible by 10 if its last digit is 0.
A number is divisible by 11 if the alternating sum of its digits is divisible by 11. Alternating sum means a-b+c-d+... – m
A number is divisible by 12 if it is divisible by 3 and 4.
The projectable version of the divisibility tests can be found here: Divisibility Tests 2-12
There is a printable worksheet to go with this activity.
The divisibility test for 7 is thanks to a 12-year old pupil, Chika Ofili, from Westminster School. You can read more about it here.
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