Focus TEKS:

  • 3.4F recall facts to multiply up to 10 by 10 with automaticity and recall the corresponding division facts;
  • 5.4A identify prime and composite numbers;
  • 5.4E describe the meaning of parentheses and brackets in a numeric expression;
  • 5.4F simplify numerical expressions that do not involve exponents, including up to two levels of grouping;

Prime and Composite Notes page 1 page 2


Prime Numbers - numbers greater than 1 that have EXACTLY 2 factors, 1 and itself.

Composite Numbers - numbers greater than 1 that have MORE THAN 2 factors.

Prime Test Example

The numbers we can use to test if a number is Prime are the numbers 2, 3, 5, and 7. Using the rules of divisibility for these numbers, we can tell if any number is a Prime or Composite Number.

Divisibility Rules

      1. Rule for 2: If the number you are testing is an EVEN number (ends in 0, 2, 4, 6, or 8), then it is divisible by 2. That means it is a COMPOSITE number.
      2. Rule for 3: Add all the digits together. If the answer you get is divisible by 3, then the number you are testing is divisible by 3. It is a COMPOSITE number.
      3. Rule for 5: If the number you are testing ends in a 0 or 5, then the number is divisible by 5. It is a COMPOSITE number.
      4. Rule for 7: Sorry! You just need to know your 7's multiplication facts! If the number you are testing is divisible by 7, then it is a COMPOSITE number.

If your number is NOT divisible by 2, 3, 5, or 7, then it is a PRIME number.


Order of Operations Notes

For 5th grade - No Exponents (that will come in 6th grade)

    1. Do all GROUPINGS (Parentheses and Brackets) first
    2. Do all MULTIPLICATION and DIVISION
      1. Whichever comes first, in order from LEFT to RIGHT
    3. Do all ADDITION and SUBTRACTION
      1. Whichever comes first, in order from LEFT to RIGHT