This includes both a Google Sheets online worksheet and a printable PDF that your students can use to practice factoring numbers. Eventually, factoring many numbers will become second nature to your students. However, when they are first learning to factor numbers, they can use divisibility rules to make the job easier. These are rules for finding out if a number can be divided by 2, 3, 5, 7, or 10. Most nonprime or composite numbers, including all such numbers between 1 and 120, can be divided