Multiplication

Review:
Multiplication As Repeated addition

Look at these examples.

There are 2 groups.

 Each group has 4 bananas

There are 3 groups.

Each group has 2 apples.

There are 3 groups.

 Each group has 3 balls.

Count the total number of groups. Count the number of objects in each group. Write the total number

There are _____ groups.

Each group has _____ eggs.

2 + 2 + 2 =_________

There are _____ groups.

Each group has _____ biscuits.

There are _____ groups.

Each group has _____ carrots.

Multiplication

How many stars are there altogether?

There are 4 groups.

Each group has 2 stars.

 2 + 2 + 2 + 2 = 8 4 × 2 = 8

 We read it as four times two equals eight

How many mangoes are there in total?

There are 3 groups.

Each group has 5 mangoes.

5 + 5 + 5 = 15 3 × 5 = 15

We read it as “three times five equals fifteen.”

Multiply the numbers.

3 × 5 =____

We say 3 times 5 equals _________.

2 × 4 =_________________

We say 2 times 4 equals _________.

3 × 7 =_________________

We say 3 times 7 equals _________.

2 × 8 =_________________

We say 2 times 8 equals _________.

Multiplication

Multiplication Tables

Let’s quickly revise the tables we learned.

Multiplication

Multiplication of a 4 - Digit Number by a 1 - Digit number

Example: Multiply 1424 by 2.

Solution:

Step 1: Write the given numbers in multiplication form.

Step 2: Multiply the ones: 4 ones × 2 = 8 ones. Write 8 under ones column.

Step 3: Multiply the tens: 2 tens × 2 = 4 tens. Write 4 under tens column

Step 4: Multiply the hundreds: 4 hundreds × 2 = 8 hundreds.

Write 8 under hundreds column.

Step 5: Multiply the thousands: 1 thousands × 2 = 2 thousands.

 Write 2 under thousands column.

So, 1424 × 2 = 2848

Multiplication

Example: Multiply 1265 by 5.

Solution:

Step 1: Write the given numbers in multiplication form

Step 2: Multiply the ones : 5 ones × 5 ones = 25 ones.

Write 5 under ones column and carry over 2 tens to tens column.

Step 3: Multiply the tens : 6 tens × 5 = 30 tens.

Add the carry over in tens: 30 tens + 2 tens = 32 tens

Write 2 under tens column and carry over 3 hundreds to hundreds column.

Step 4: Multiply the hundreds : 2 hundreds × 5 = 10 hundreds.

Add the carry over in hundreds: 10 hundreds + 3 hundreds = 13 hundreds

Write 3 under hundreds column and carry over 1 thousand to thousands column.

Step 5: Multiply the thousands : 1 thousand × 5 = 5 thousands

Add the carry over in thousands: 5 thousands + 1 thousand = 6 thousands

Write 6 under thousands column.

So, 1265 × 5 = 6325

Multiplication

Multiplication By Two Digit Numbers
Example: Multiply 65 by 32.

Solution:

Step 1: Write the given numbers in multiplication form.

Step 2: Multiply 65 by 2 ones : 65 × 2 ones = 130 ones.

Write 130 ones below the line.

Step 3: Multiply 65 by 3 tens: 65 × 3 tens = 195 tens

= 1950 ones.

Write 1950 ones below the first product.

Step 4: Add both the products : 130 + 1950 = 2080.

So, 65 × 32 = 2080

Example: Multiply 113 by 22.

Solution:

Step 1: Write the given numbers in multiplication form.

Step 2: Multiply 113 by 22 ones : 113 × 22 ones = 226 ones.

Write 226 ones below the line.

Step 3: Multiply 113 by 22 tens: 113 × 22 tens = 226 tens

= 2260 ones.

Write 2260 ones below the first product.

Step 4: Add both the products : 226 + 2260 = 2486.

So, 113 × 22 = 2486

Multiplication

Properties Of Multiplication
Property 1: Numbers can be multiplied in any order.

The product remains the same.

 For example: 4 × 5 = 5 × 4 = 20

Look at the picture.

We can describe this picture in 2 ways.

There are 3 groups.

Each group has 5 balls

3 × 5 = 15

There are 5 groups

Each group has 3 balls.

5 × 3 = 15

5 × 3 = 3 × 5

Property 2:

When a number is multiplied by 0, the product is always 0.

For example: 769 × 0 = 0

Look at this box. Are there any apples?

There are 0 apples.

What if we have three such boxes? How many apples do we have then?

We still have 0 apples. 3 × 0 = 0

If we multiply anything by 0, the answer is still 0.

5 × 0 = 0

Complete the following.

4 × 0 = 0          0 × 6 = 0         9 × 0 = 0

Property 3:

 When a number is multiplied by 1, the product is the number itself.

For example: 99 × 1 = 99

Some other Properties

Observe the following:

We observed that to multiply a given number by 10, 100 or 1000, we insert as many zeros to the right of the number as the number of zeros in the multiplier.

Multiplication

Henry has 6 sweets. Lucy has also 6 sweets. How many sweets do they have in total?

There are 2 children. Each child has 6 sweets.

2 × 6 = 12 (2 times 6 = 12)

 Henry and Lucy have 12 sweets in total.

John, Lucas and Sara have 10 balls each. How many balls are altogether?

There are 3 children. Each child has 10 balls.

3 × 10 = 30

There are 30 balls in total.