I am working on converting old anchor charts and notes to typed posters.
Divisibility Rules Poster Options:
Black and White:
Use these photos as a poster to display in your classroom, or print for use in student notebooks/binders. Here is the FREE .pdf: DivisibilityRulesPoster.
So, what is this trick for the 7’s divisibility rules?
Check it out:
- Double the last digit and subtract it from the remaining part of the number. If the answer is either 0 or it is divisible by 7, then the original number is divisible by 7.
- Start with the number: 1015.
- Isolate the last digit: 1015 .
- Double the last digit. 5 x 2 = 10.
- Subtract the result (10) from the remaining part of the number (101): 101 – 10 = 91
- Determine whether your answer is equal to 0 or divisible by 7. If it is, the number is divisible by 7. If it is not, the number is not divisible by 7.
- 91 divided by 7 equals 13, which is a whole number.
- Since 91 is divisible by 7, that means 1015 is also divisible by 7.
- If you are curious, and don’t feel like working it out… 1015 divided by 7 equals 145.
It is probably easier just to do long division in most cases, but it is always fun to learn a new trick 😉