Today We Are Learning How To Multiply : Today We Are Learning How To Multiply
Understanding Multiplication : 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 : 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 : 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
4 + 4 + 4 = 12
Understanding Multiplication : 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 : 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 : 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 : 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 : Multiplication Using Skip Counting We could also skip count by 4.
4 8 12
Multiplication Using Arrays : 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 : 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 : 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 : Understanding Multiplication Now that we have reviewed several ways for understanding multiplication lets review the multiplication table on the next slide.
Multiplication Table : Multiplication Table Look at the multiplication table below.
Multiplication Table : 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 : Multiplication Table See the shaded area in the table below.
3X9=27
Understanding Multiplication : 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 : Understanding Multiplication There are three different ways you can write a multiplication sign:
1. You can use the multiplication (times) sign:
2 X 4 = 8
2. A dot between the numbers:
2 ∙ 4 = 8
3. Parentheses:
(2) (4) = 8
Understanding Multiplication : Understanding Multiplication Multiplication can also be shown:
Horizontally → 9 X 6 = 54
or
Vertically
↓
9
X 6
54
When it is shown vertically, the bar under the second factor represents the equal sign.
Understanding Multiplication : Understanding Multiplication The zero multiplication facts:
Any number times zero is always zero.
Multiplication is repeated addition so:
0 X 3 = 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.
3 X 0 = 0 or 0 X 3 = 0
( The numbers can be switched around and the answer is still the same. This is true for all multiplication problems.)
Understanding Multiplication : Understanding Multiplication The 1’s multiplication facts:
Any number times 1 is always itself.
Multiplication is repeated addition so:
1 X 4 = 4 → 1 + 1 + 1 + 1 = 4
Because of the commutative property of
multiplication:
1 X 4 = 4 or 4 X 1 = 4
Understanding Multiplication : Understanding Multiplication The 2’s multiplication facts:
Any number times 2 is that number doubled.
Multiplication is repeated addition so:
2 X 4 = 8 → 4 + 4 = 8
Because of the commutative property of multiplication:
2 X 4 = 8 or 4 X 2 = 8
Understanding Multiplication : Understanding Multiplication This concludes Part 1 on learning how to multiply.
Multiplication : Multiplication THE
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