# Homework Tips for the Week of January 13, 2014

This week we will be working on divisibility rules and prime/composite numbers. Your child should have a page with all of the divisibility rules on it (apple page). For extra help at home, ask your child to tell you how they know if a number is divisible by each number. For example,
Parent: “A number is divisible by two when . . .”
Child: “it ends in an even number like 0, 2, 4, 6, or 8.”
We also will be working on prime and composite numbers. Prime numbers are numbers that only have 2 factors—1 and itself. For example: The number 3 is prime because its only factors are 1 and 3 (1 x 3 = 3). However 4 is composite because its factors are 1, 2, and 4. ( 1 x 4 = 4 and 2 x 2 = 4).
Prime Factorization–A factor tree is one method of determining the prime factorization of a number. The method is based on writing a number as a product of two factors, each greater than 1. Each of these factors is then written as a product of two factors, each greater than 1. The process continues until each factor at the end of a “branch” is a prime number. Every whole number greater than 1 has a unique prime factorization. The prime factorization of 40 is 2 x 2 x 2 x 5, regardless of the pair of factors used in the first step.