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Number - Multiplication and Division Facts

Grade 3IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Multiplication as Repeated Addition: Multiplication is a shortcut for adding the same number multiple times. Imagine a picture of 3 baskets, each containing 4 apples; this can be seen as 4+4+44 + 4 + 4, which is written as 3×4=123 \times 4 = 12.

Understanding Arrays: An array is a visual arrangement of objects in equal rows and columns. For example, a grid of dots with 2 horizontal rows and 5 vertical columns represents 2×5=102 \times 5 = 10. This helps us see that the total count is the product of the rows and columns.

Division as Equal Sharing: Division is the process of splitting a large group into smaller, equal parts. If you have 15 stickers and share them equally among 3 friends, you can visualize 3 circles with 5 stickers inside each circle, representing 15÷3=515 \div 3 = 5.

Division as Equal Grouping: This involves finding how many groups of a certain size can be made from a total. If you have 20 cookies and put 4 on each plate, you are finding how many plates (groups) are needed: 20÷4=520 \div 4 = 5.

Commutative Property of Multiplication: The order of the numbers does not change the product. Visually, turning a 3×43 \times 4 array (3 rows, 4 columns) on its side makes it a 4×34 \times 3 array (4 rows, 3 columns), but both still contain 12 items. So, a×b=b×aa \times b = b \times a.

The Relationship Between Multiplication and Division (Fact Families): These operations are opposites (inverses). If you know 4×5=204 \times 5 = 20, you also know 20÷5=420 \div 5 = 4 and 20÷4=520 \div 4 = 5. They form a 'Fact Family' triangle with 20 at the top and 4 and 5 at the bottom corners.

Multiplying by 0 and 1: Any number multiplied by 1 stays the same (n×1=nn \times 1 = n), like 1 group of 5 items. Any number multiplied by 0 equals 0 (n×0=0n \times 0 = 0), like having 5 empty bags with nothing inside.

Skip Counting and Multiples: Multiples are the products of a number and any whole number. On a number line, skip counting by 3s (3,6,9,12...3, 6, 9, 12...) shows the multiples of 3, which are the answers to the 3 times table.

📐Formulae

Factor×Factor=Product\text{Factor} \times \text{Factor} = \text{Product}

Total÷Number of Groups=Size of Each Group\text{Total} \div \text{Number of Groups} = \text{Size of Each Group}

Total÷Size of Each Group=Number of Groups\text{Total} \div \text{Size of Each Group} = \text{Number of Groups}

a×b=b×aa \times b = b \times a

n×1=nn \times 1 = n

n×0=0n \times 0 = 0

n÷1=nn \div 1 = n

💡Examples

Problem 1:

Sarah has 4 boxes. Each box has 6 toy cars. How many toy cars does she have in total? Write a multiplication sentence and use repeated addition to solve.

Solution:

Step 1: Identify the groups and the size. Groups = 4 boxes, Size = 6 cars. Step 2: Write as repeated addition: 6+6+6+6=246 + 6 + 6 + 6 = 24. Step 3: Write as a multiplication sentence: 4×6=244 \times 6 = 24.

Explanation:

We use multiplication to find the total when we have multiple groups of the same size. Adding 6 four times is the same as multiplying 4 by 6.

Problem 2:

There are 18 cupcakes to be shared equally among 3 children. How many cupcakes does each child get? Show the related multiplication fact.

Solution:

Step 1: Identify the total (18) and the number of groups (3). Step 2: Set up the division: 18÷3=618 \div 3 = 6. Step 3: Find the related multiplication fact: 3×6=183 \times 6 = 18.

Explanation:

To solve a division problem, we can ask ourselves '3 times what number equals 18?'. Since 3×6=183 \times 6 = 18, then 18÷3=618 \div 3 = 6.