Power Point Year 3

Today We Are Learning How To Multiply

SK KHIR JOHARI SABAK BERNAM

Understanding Multiplication



When the same numbers are added over and over again, a simpler way of reaching the same result is to use multiplication.

Understanding Multiplication 

Example: If you know there are 5 pennies in every nickel and you have 7 nickels, how would you figure out how many pennies are in 7 nickels? You could add 5, seven times: 5+5+5+5+5+5+5= 35 or You could simply multiply 5 X 7 = 35

Understanding Multiplication 

Read the multiplication word problem below. Each house has four people living in it. How many people live in the houses? 3 × 4 = 12 people

12

4 +

4

+

4=

Understanding Multiplication  There

are 7 rocks in each box. That is a total of how many rocks?

7

+

7

+ 7 + 7

= 28

4X7 = 28

Understanding Multiplication  The

easiest way to find the total number of items in equal groups is to use multiplication.  Multiplication allows you to do repeated addition quickly and efficiently.

Multiplication Using Grouping  Another

way to look at it would be equal grouping. We are going to use 3X4 as our example. Example: 3X4=12 Lets interpret 3X4 as 3 groups of 4.

Multiplication Using Grouping Lets find 3X4 by counting the dots one by one.

4 +4 +4 = 12 You see 3 groups of 4. Therefore 3X4 = 4 + 4 + 4 Multiplication can be solved by repeated addition.

Multiplication Using Skip Counting  We

could also skip count by 4.

4

8

12

Multiplication Using Arrays  Lets

use another approach to understanding multiplication. We will now use an array. You are going to be able to represent 3X4 not as 3 separate groups, but as 3 rows of 4 objects as shown below.

Multiplication Using Arrays  Can

you see 3 groups of 4 in the array. Each row represents 3 groups of 4.

Now can you see 4 groups of 3. Each column represents 4 groups of 3.

Multiplication Using Arrays and Skip Counting  Lets

use the array below to use the strategy of skip counting. The array below shows 4X8 drawn as an array of 4 rows of 8 dots.

4

8 12 16 20 24 28 32

Understanding Multiplication  Now

that we have reviewed several ways for understanding multiplication lets review the multiplication table on the next slide.

Multiplication Table  Look

at the multiplication table below.

Multiplication Table  Use

the multiplication table to find the product of 3 and 9, locate 3 in the first column and then find 9 in the top row.  Follow the 3 row to where it meets the 9 column.  The number in the square where the column and row meet is the product

Multiplication Table See the shaded area in the table below. 3X9=27

Understanding Multiplication 

When multiplying numbers it is important you know the following terms:

1. Factors 2. Products Factors – are the numbers being multiplied. Products – are the result of multiplication (simply put the answer).

Understanding Multiplication  There

are three different ways you can write a multiplication sign: 1. You can use the multiplication (times) sign: 2X4=8 2. A dot between the numbers: 2∙4=8 3. Parentheses: (2) (4) = 8

Understanding Multiplication 

Multiplication can also be shown: Horizontally

→ or

9 X 6 = 54

Vertically ↓ 9 X 6 54 When it is shown vertically, the bar under the second factor represents the equal sign.

Understanding Multiplication The zero multiplication facts: Any number times zero is always zero. Multiplication is repeated addition so: 0X3=0 →0+0+0=0 It does not matter which number is first when you write the problem. The answer is the same. This is called commutative property of multiplication. 3X0=0 or 0X3=0 ( The numbers can be switched around and the answer is still the same. This is true for all multiplication problems.)

Understanding Multiplication The 1’s multiplication facts: Any number times 1 is always itself. Multiplication is repeated addition so: 1X4 =4 → 1+1+1+1=4 Because of the commutative property of multiplication:

Understanding Multiplication The 2’s multiplication facts: Any number times 2 is that number doubled. Multiplication is repeated addition so: 2X4=8 → 4+4=8 Because of the commutative property of multiplication: 2X4=8 or 4 X 2 = 8

Understanding Multiplication 

This concludes Part 1 on learning how to multiply.

Multiplication

THE END