Exercise
If x, y and z are integers then
x·y·z is a multiple of 27 if and only if
x, y or z is a multiple of 27
x·y·z is a multiple of 29 if and only if
x, y or z is a multiple of 29
x·y·z is a multiple of 25 if and only if
x, y or z is a multiple of 25
No, take x, y and z all to be equal to 3
Indeed, as 29 is prime we find that 29 divides one of x, y or z
No, take x, y and z all to be equal to 5