Final answer:
To know when you can stop looking for factors in a number, consider if you have found all prime factors, exhausted all possible factors, or found a factor and its corresponding pair.
Step-by-step explanation:
You can stop looking for factors in a number when the quotient is smaller than the divisor or when a prime factor is found.
To find the factors of a number, you can start by dividing the number by 2 and continue dividing by the next consecutive odd number until the quotient is smaller than the divisor. If you find that the number is divisible by a number other than 2, then you can stop dividing by odd numbers and start dividing by the next prime number (3, 5, 7, etc.) until the quotient is smaller than the divisor or until you find that the number is divisible by a prime number.
For example, to find the factors of the number 12, you would start by dividing 12 by 2 and continue dividing by the next consecutive odd number until you find that 12 is divisible by 3. At this point, you would stop dividing by odd numbers and start dividing by the next prime number (5). You would find that 12 is not divisible by 5, so you would stop dividing by prime numbers.
Therefore, the factors of 12 are 1, 2, 3, 4, 6, and 12.