3rd Class Mathematics Multiplication Multiplication

LEARNING OBJECTIVES

This lesson will help us to:

• Recognize multiplication as repeated addition.
• Explain the concept of multiplication as repeated addition.
• Identify the sign of multiplication.
• Construct the multiplication tables of 2, 3, 4, 5 and 10.
• Write multiplication facts for 2, 3, 4, 5 and 10.
• Use the multiplication facts in various situations.

REAL LIFE EXAMPLES

• If you want to buy 5 dozens of eggs and each dozen contains 12 eggs, then you need to multiply 5 and 12 which is 5 X 12 = 60 So, you can calculate the total number of eggs in 5 dozens.
• If you are going out on a picnic and you have 3 cars with you and 5 people can sit in each car then you need to use multiplication skills to calculate the total number of persons that can go for picnic i.e. 3 X 5 = 15 persons.
• While celebrating your birthday party, you want to decorate your room with balloons and you want to place 8 balloons on each wall and there are 4 walls in a room, then you need to multiply 8 and 4 to find out the total number of balloons you need to buy i.e. 8 X 4 = 32

QUICK CONCEPT REVIEW

Multiplication is repeated addition. The number to be multiplied is the multiplicand, the number we are multiplying with is the multiplier and the result is called the product of multiplication.

Examples

1.  This is a flower. It has 8 petals. How many petals are there in 5 such flowers?

8+8+8+8+8= 40, or 5 times 8 = 40,

Or 5 x 8 = 40

2.  This is an ant. It has 6 legs. How many legs do 7 ants have altogether?

6+6+6+6+6+6+6= 42, or 7 times 6 = 42.

Or 7 X 6 = 42

3.   This is a tray with Ladoos (sweet). It has 9 Ladoos. How many Ladoos are there in 6 trays?

9+9+9+9+9+9=54, Or 6 times 9 = 54,

or 6 X 9 = 54

MULTIPLICATION TREE

10 \[\Rightarrow \]1X 10 =2X5=5X2

35 \[\Rightarrow \]1X 35 =5X7=7X5

24 \[\Rightarrow \]1X24=2X12=3X8

=4X6

18 \[\Rightarrow \]1X 18=2X9=3X6

                =9X2

36 \[\Rightarrow \]1 X 36 = 2 X 18 = 3 X 12

                =4X9=6X6

32\[\Rightarrow \]1X32=2X16=4X8

                = 8 X 4 = 16 X 2

THINGS THAT COME IN GROUPS

Amazing Facts

• When any number is multiplied by one, the product is the number itself.

145 X 1 = 145

• When any number is multiplied by zero, the product is always zero.

326 X 0 = 0 or 0 X 242 = 0

• Two numbers multiplied in any order give the same product.

120 X 2 = 240 or 2 X 120 = 240

HISTORICAL PREVIEW

• People in Egypt, China and India used to practice multiplication in different forms.
• The multiplication table used today was invented by victories of Aquitaine in 493 Ad
• John Leslie publishes a multiplication table up to 99 x 99 in his book ‘The philosophy of Arithmetic’ in the year 1820, which allows numbers to be multiplied in pairs of digits at a time.
• Lattice multiplication is a way of multiplying large numbers by using a drawn grid. It was invented in Europe in 1202 and is frequently used in schools today.
• The multiplication sign ‘X’ was introduced by ought red in 1631.

MULTIPLICATION CHART

SHORTCUT TO PROBLEM SOLVING

1. To write the table of 4, the trick to multiply the given number by 2 two times. For example, 4 X 3 can be solved as 3 X 2 = 6 then 6 X 2 = 12, so 4 X 3 = 12.
2. To write the table of 9, the trick is to write the numbers from 1 to 8 while going down and then again while coming back up except 9 and 90 because they are always equal to 9. For example, 2 + 7 = 9 , 6 + 3 = 9 , etc.

Step1:                 Step 2:

9 X 1 = 9            9 X 1 = 9

9 X 2 = 1            9 X 2 = 18

9 X 3 = 2            9 X 3 = 27

9 X 4 = 3            9 X 4 = 36

9 X 5 = 4            9 X 5 = 45

9 X 6 = 5            9 X 6 = 54

9 X 7 = 6            9 X 7 = 63

9 X 8 = 7            9 X 8 = 72

9 X 9 = 8            9 X 9 = 81

9 X 10 = 9          9 X 10 = 90

3. If you know 6 X 5 = 30, then you can answer 5X6= 30. If you know the answer to one of the facts then you can answer the other one too.
4. If you want to multiply any number with 10, just write '0' after that number. For example, 10 X 5 = 50.
5. If you want to multiply any number with 11, just write the number two times. For example, 11 X 7 = 77.
6. To multiply a number by 12, first multiply the number by 2 then by 10 then add the two answers. For example, for 12 X 3, 3 X 2 = 6 and 3 X 10 = 30 so. 12 X 3 = 6 + 30 = 36. Hence, 12 X 3 = 36.