today we will review the chapter:
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CONFIDENTIAL 1
Today we will review the Chapter:Whole Numbers – Multiplying & Dividing
Good Afternoon!
Let’s Warm up:.
1) 6 x 4 = 2) 11 x 3 =
3) 8 x 5 = 4) 7 x 6 =
CONFIDENTIAL 2
Let's Review Factors & Multiples
Factor: Number that is multiplied to give a product.
Product: Number that is obtained by multiplying numbers.
Multiplication by a whole number is REPEATED ADDITION
CONFIDENTIAL 3
There are several properties of multiplication.
1) COMMUTATIVE PROPERTY:We can change the order of the factors and the product stays the
same.EXAMPLE: 4 x 3 = 12
3 x 4 = 122) IDENTITY PROPERTY:We can multiply a number by 1 and the product is the
number. EXAMPLE: 3 x 1 = 3
3) ZERO PROPERTY:We can multiply a number by 0 and the product is
zero. EXAMPLE: 7 x 0 = 0
CONFIDENTIAL 4
Complete each problem using the COMMUTATIVE PROPERTY.
"Change the Order"
6 x 3 = x
2 x 5 = x
CONFIDENTIAL 5
Complete each problem using the IDENTITY PROPERTY.
6 x 1 =
5 x 1 =
CONFIDENTIAL 6
Complete each problem using the ZERO PROPERTY.
0 x 3 =
6 x 0 =
CONFIDENTIAL 7
Patterns to Multiply by 2, 10, 100 etc.
We learnt about the following terms:
Multiple: It is the product of a number and any whole number.
Even numbers: Whole numbers that are divisible by 2 are even numbers.
Odd numbers: Whole numbers that are not divisible by 2 are odd numbers.
Prime numbers: Numbers whose factors are only 1 and the number itself are prime numbers.
Composite numbers: All the non-prime numbers except 0 and 1, are Composite Numbers.
CONFIDENTIAL 8
We can multiply by the means of Skip Counting also.
By Skip Counting we mean that we can find the multiples of any number by hopping equal steps on the number line.
0 1 2 3 4 5 6
2 2 2
There are other strategies that can be used for multiplication.Find 7 x 3.
Use a Known Fact
7 groups of 3 = 7 groups of 2 plus 7 7 x 3 = 7 x 2 +
7 = 14 + 7 = 21
Here the numbers are
taking 3 jumps each of
2 steps.
Double a Known Fact
Find 8 x 6.
8 x 6 = (4 x 6 ) + (4 x 6)
= 24 + 24 = 48
8 groups of 6 = 4 groups of 6 + 4 groups of 6
CONFIDENTIAL 9
We looked into the Multiplication Table and its patterns now:
x 0 1 2 3 4 5 6 7 8 9 10 11 12
0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 0 1 2 3 4 5 6 7 8 9 10 11 12
2 0 2 4 6 8 10 12 14 16 18 20 22 24
3 0 3 6 9 12 15 18 21 24 27 30 33 36
4 0 4 8 12 16 20 24 28 32 36 40 44 48
5 0 5 10 15 20 25 30 35 40 45 50 55 60
6 0 6 12 18 24 30 36 42 48 54 60 66 72
7 0 7 14 21 28 35 42 49 56 63 70 77 84
8 0 8 16 24 32 40 48 56 64 72 80 88 96
9 0 9 18 27 36 45 54 63 72 81 90 99 108
10 0 10 20 30 40 50 60 70 80 90 100 110 120
11 0 11 22 33 44 55 66 77 88 99 110 121 132
12 0 12 24 36 48 60 72 84 96 108 120 132 144
In the table, the pattern of the square numbers are shown within the yellow
squares.
CONFIDENTIAL 10
Find the products of the following:
1) 3 x 4 = 2) 7 x 2 =
3) 9 x 9 = 4) 5 x 5 =
CONFIDENTIAL 11
Multiplication is an operation on two numbers to find a product. Like 3 x 4 = 12.
ASSOCIATIVE PROPERTY:While multiplying, we can change the grouping of the factors and the
product stays the same.EXAMPLE: 2 x (3 x 4) = (2 x 3) x 4
Multiply 2-4 digit by 1 digit
You can use pattern of factors and products to multiply mentally.3 x 2 = 6
3 x 20 = 60
3 x 200 = 600
3 x 2,000 = 6,000
CONFIDENTIAL 12
We multiply numbers by first lining up the digits.
236X 6
First multiply 6 with 6 to obtain 36.
6
3
STEP 1:
Regroup 36 as 3
tens and 6 ones.
236X 6
Again, multiply 6 with 3 at the tens place to obtain 18.
Then, add 3 and 18 to obtain 21.
16
23
STEP 2:
Regroup 21 as 2
hundreds and 1 tens.
CONFIDENTIAL 13
236X 6
Then, multiply 6 with 2 at the hundreds place to obtain 12.
Then, 2 and 12 to obtain 14.
1416
23
STEP 3:
Hence, the
result.
Estimate 6 x 44.
By Estimate, we mean an answer that is close to the exact answer.
While estimating products, we round the greater factor.
6 x 44.
6 x 40 =240
Round to the
nearest tens.
CONFIDENTIAL 14
Overestimate: It is estimate greater than the exact answer.Underestimate: It is estimate less than the exact
answer.
We also use the Distributive Property to multiply.
Split 3,839 into 4 parts:3,000 + 800 + 30 + 9
5 x 3,000 =15,0005 x 800 = 4,000
5 x 30 = 1505 x 9 = 45
Then finally add each part:15,000 + 4,000 + 150 + 45 =
19,195
Multiply: 5 x 3,839
Then multiply each part by 5:
CONFIDENTIAL 15
Estimate the products of the given problems:
1) 6 x 44 2) 7 x 48
CONFIDENTIAL 16
Multiply using the Distributive Property :
1) 6 x 694 2) 2 x 7,295
CONFIDENTIAL 17
Multiply 2-3 digit by 2 digit
45X 21
Multiply by the ones. Regroup if
necessary.
45
STEP 1:
Example: To find 21 x 45
45X 21
Multiply by the tens. Regroup if necessary.
45
STEP 2:
900
45X 21
Add the products.
45
STEP 3:
+900945
1
You can use the Distributive Property to
break apart the factors: (1 x 45) + (20
x 25)
Use a zero to show that you are multiplying
by tens.
CONFIDENTIAL 18
Multiply 2-3 digit by 2 digit
Your Turn! Find 19 x 67
CONFIDENTIAL 19
Let us take a break!
CONFIDENTIAL 20
Jig-Saw puzzle
• http://www.thekidzpage.com/onlinejigsawpuzzles/jigsaw-puzzles/12-piece-jigsaw/snowman1.html
Let us see how fast you are on this one!
CONFIDENTIAL 21
Patterns to Divide and Division facts
• Division: An operation on two numbers that tells how many groups or how many in each group.
• Dividend: A number to be divided.• Divisor: The number by which the dividend is divided.• Quotient: The result of division.
CONFIDENTIAL 22
Patterns to Divide and Division facts
• Use Models
Find how many groups of 5 are in 10
counters.
STEP 1:
Find how many counters are in each group if you put 10
counters in 2 equal groups
STEP 2:
Total Number of Groups
Number in Each Group
10 5
10 ÷ 2 = 510 divided by 2 equals 5
Total Number of Groups
Number in Each Group
10 2
10 ÷ 5 = 210 divided by 5 equals 2
CONFIDENTIAL 23
Patterns to Divide and Division facts
• Your Turn! • Use models to find
– how many are in each group: 12÷6– 35 has how many groups of 5?
CONFIDENTIAL 24
Patterns to Divide and Division facts
0 1 2 3 4 5 6
2 2 2
Use a related multiplication fact to help you divide32 ÷ 8 = 4
Think:_ x 8 = 324 x 8 = 32
Use a Number Line
6 ÷ 2 = 3There are 3 jumps from 6 to 0
Multiplication and division are inverse operations.
CONFIDENTIAL 25
Dividing with Remainders
• Remainder The number less than the divisor that remains after division is completed.– 31 ÷ 6 = 5 R1. – 1 is the remainder.
CONFIDENTIAL 26
Division by 1-digit divisors
• You can use models to divide (Example: 57 ÷ 4)STEP 1: Show 57 as 5 tens and 7 ones. Draw rectangles to show 4 groups.
STEP 2: Place an equal number of tens in each group.
Regroup 1 ten and 7 ones as 17 ones.
CONFIDENTIAL 27
Division by 1-digit divisors
• You can use models to divide (Example: 57 ÷ 4)
STEP 3: Place an equal number of ones in each group.
There will be 1 one left. This is the remainder.
CONFIDENTIAL 28
Division by 1-digit divisors
• Your Turn! Use models to divide 136 ÷ 4
CONFIDENTIAL 29
Division by 1-digit divisors
• Find: 148 ÷ 3
STEP 1:
Estimate to place the first digit.3 148 Think: 3 1hundred
Not enough hundreds to divide
3 148 Think: 3 14 tensEnough tens to divide
3 148x
The first digit is in the tens place.
STEP 2:
Divide the tens.Think:
3 x 4 tens = 12 tens3 x 5 tens = 15 tens
5 tens are too high.So use 4 tens.
3 1484
-122
Multiply 3 x 4Subtract 14 – 12Compare: 2 < 3
CONFIDENTIAL 30
Division by 1-digit divisors
• Find: 148 ÷ 3
STEP 3:
Bring down the ones and divide.
STEP 4:
3 14849-
1228-27
1Multiply 3 x 9Subtract 28 – 27Compare: 1 < 3
The amount left over is the remainder.
Check the answer.Multiply the quotient by the divisor. 49
x 3147Then add the
remainder.+ 1
148
148 ÷ 3 = 49 R1
Quotientdivisor
remainderdividend
CONFIDENTIAL 31
Division by 1-digit divisors
• Your Turn! Find: 935 ÷ 8
CONFIDENTIAL 32
Division by 2-digit divisors
• Use Models to find: 115 ÷ 12
STEP 1: Show 115 using place-value models.Regroup the hundreds as tens.
STEP 2: Regroup the tens as needed.
CONFIDENTIAL 33
Division by 2-digit divisors
• Use Models to find: 115 ÷ 12
STEP 3: Form 12 groups.Regroup more tens.
Count the number of ones in each group.There are 9 ones in each group.
Count the number of ones left.There are 7 ones left (the remainder).
CONFIDENTIAL 34
Division by 2-digit divisors
• Find: 184 ÷ 13
13 1841
-135
13 tens used5 tens left
1 ten in each group
13 184 14
-1354
Bring down 4 ones.54 ones in all.
13 184 14R2-13
54 52 ones used.-522 The 2 left is the remainder.
CONFIDENTIAL 35
Division by 2-digit divisors
• Your Turn! Find: 3,470 ÷ 55
CONFIDENTIAL 36
Word problems
• A team wants to sell 240 books to raise money. If there are 15 players, what is the number of books each player must sell?
CONFIDENTIAL 37
Word problems
• Skate laces are available in boxes of 20 pairs for $30 or boxes of 100 pairs for $120. Which is the better buy? Why?
CONFIDENTIAL 38
Assessment
Find the product with the help of model.
1) 2 x 2 =
2) 7 x 3 =
CONFIDENTIAL 39
Assessment
Find the product:
573X 3
924X 17
3) 4)
CONFIDENTIAL 40
Assessment
Divide.
5) 1,323 ÷ 4 6) 3,572 ÷ 77
CONFIDENTIAL 41
Assessment
Solve. What number am I?
7) I am a number between 10 and 20. If you divide either 61 or 73 by me, the remainder is 1.
8) I am a number between 10 and 20. If you divide either 45 or 56 by me, the remainder is 1.
CONFIDENTIAL 42
Assessment
9) There is $180 to build 12 booths. How much money is there fro each booth?
10) There are 5,000 cups for lemonade at the carnival. The lemonade will be served at 12 tables. How many cups are on each table? How many cups are left over?
CONFIDENTIAL 43
Good Job!
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