** Domiprime is a game of strategy using prime numbers. **

A number is said to be prime if its only divisors are 1 and itself. For instance 2, 3, 5...

There are infinitely many primes and any number greater or equal to 2 can be written as a unique product of primes.

For instance : 4=2*2; 6=3*2; etc...

** A NUMBER WITH THREE FIGURES WILL BE WRITTEN "ABC". For instance 123, A=1, B=2 et C=3. **

We remind a few divisibility rules for numbers with three figures which might be especially useful at the Expert Level.
Let us start with simple rules.

** A number is a multiple of 2 if its last figure is even. **

** A number is a multiple of 4 if "BC" or 2*B+C is a multiple of 4. Example 624, for BC=24 is a multiple of 4 OR 2*B+C=2*2+4=8 as well. **

** A number is a multiple of 3 if the sum of its figures is a multiple of 3. **

** A number is a multiple of 9 if the sum of its figures is a multiple of 9. **

** A number is a multiple of 5 if its last figure is 5 or 0. **

** A number is a multiple of 11 if its middle figure is equal to the sum of the two others. Example 143 for 4=1+3. Or 88=088 because 8=0+8. **

** A number is a multiple of 7 if "AB"-2*C is a multiple of 7. Example 392 for 39-2*2=35 is a multiple of 7. **

** A number is a multiple of 19 if "AB"+2*C is a multiple of 19. Example 437 for 43+2*7=57 is a multiple of 19. **

** A number is a multiple of 13 if "AB"+4*C is a multiple of 13. Example 676 for 67+4*6=91 and 091 gives 9+4*1=13 which is a multiple of 13. **

** A number is a multiple of 17 if "AB"-5*C is a multiple of 17. Example 306 for 30-5*6 =0 is a multiple of 17. **

** A number is a multiple of 23 if "AB"+7*C is a multiple of 23. Example 437 for 43+7*7=92 is a multiple of 23. **

** A number is a multiple of 29 if "AB"+3*C is a multiple of 29. Example 986 for 98+3*6=116 and 11+3*6=29 is a multiple of 29. **

** A number is a multiple of 31 if "AB"-3*C is a multiple of 31. Example 775 for 77-3*5=62 is a multiple of 31. **