Multiplication by Regrouping | Term 2 Unit 1 Numbers | 3rd Maths

Chapter: 3rd Maths : Term 2 Unit 1 : Numbers

Multiplication by Regrouping

Understanding Multiplication Methods

Multiplication of a number with other number can be done in the following ways.

(i) Dot multiplication

(ii) Repeated addition

(iii) Regrouping

(iv) Standard multiplication algorithm

(v) Lattice multiplication

Multiplication by Regrouping

This method can be used by multiplying a two digit number.

Consider the following multiplication:

53 × 7

53 can be regroup into 5 tens and 3 ones.

Hence, 53 × 7 can be written as (50 + 3) × 7

= (50 × 7) + (3 × 7)

= 350 + 21

= 371.

Example

14 × 2 = ?

That is 2 Times 14

14 × 2 = 2 × 1 Ten + 2 × 4 Ones

= 2 × 10 + 2 × 4 = 20 + 8

= 14 × 2 = 28

Exercise

1. Multiply the following numbers by regrouping

(i) 75 × 8

= (70 + 5) × 8

= (70 × 8) + (5 × 8)

= 560 + 40

= 600

(ii) 26 × 5

= (20 + 6) × 5

= (20 × 5) + (6 × 5)

= 100 + 30

= 130

(iii) 372 × 6

= (370 + 2) × 6

= (370 × 6) + (2 × 6)

= 2220 + 12

= 2232

(iv) 402 × 7

= (400 + 2) × 7

= (400 × 7) + (2 × 7)

= 2800 + 14

= 2814

(v) 752 × 3

= (750 + 2) × 3

= (750 × 3) + (2 × 3)

= 2250 + 6

= 2256

Information Processing: Listing All Possible Ways | 3rd Maths Term 1 Unit 6

3rd Maths : Term 1 Unit 6 : Information Processing

Listing down all possible ways

Example 1: Trousers and Shirts

Kavin has taken 2 trousers and 3 shirts with him to wear in a picnic. list down all the possible choices that he can wear them.

Here are the choices.

There are two possible ways of dressing using one shirt and two trousers as shown in picture 1. Similarly we shall pair remaining two shirts with the trouser in four ways as shown in picture 2 and picture 3.

Hence there are six possible ways of pairing two trouser with three shirts.

Example 2: Fruits and Vegetables

Kaviya likes to eat one vegetable and one fruit in a day. Apples and oranges are her choices among fruits and carrots and cucumbers are her choices among vegetables. Complete the given table by filling the ways she combine one fruit with one vegetable.

Example 3: Three-Digit Numbers

List down all possible ways of forming three digit numbers by using the digits 4, 5 and 7 once.

Possible ways

Practice

1. List down all possible ways of forming three digit numbers by using the given digits only once.

a. 9, 6, 8

b. 3, 2, 0

c. 1, 5, 4

Possible ways

a. 986 968 698 689 896 869

b. 320 302 230 203 032 023

c. 154 145 415 451 541 514

2. Find all possible ways of combining the three letters a, e, t using each of them once.

Possible ways

Activity 1

Let us colour the blocks.

Find all possible ways of colouring the given blocks with blue and red. One is done for you.

Activity 2

Fill the white space in the given blocks with alternate colours and answer the following questions based on it.

1. Total number of blocks: 2

2. Number of rose block: 4

3. Number of blocks: 6

4. Number of blocks in 2 and 4 row: 1 & 2

5. How many more than : 2

Example 4: Words Starting with 'R'

List all possible 3 lettered words 4 lettered words and 5 lettered words that start with alphabet ‘R’.

Look at the above words and answer the questions.

1. Number of 4 lettered words are ___.

2. Number of words with 5 letters are ___.

3. There are ____ 3 lettered words.

4. There are ____ 5 lettered words.

List Down All Possible Words

List down all possible meaningful 3 lettered and 4 lettered words starting with the alphabet ‘A’.

Activity 3

List the names of the animals with 4 letters.

Deer, goat, lamb and lion

3rd Maths: Numbers - Ordering Concepts and Practice Exercises | Term 1 Unit 2

3rd Maths : Term 1 Unit 2 : Numbers

Topic: Ordering

Understanding Ordering

Ordering

Consider the numbers 2 and 7. By using these numbers we shall form the greatest and smallest two digit numbers. The two−digit numbers formed using 2 and 7 are 27,72,22,77. (77 is the greatest and 22 is the smallest 2 digit numbers)

Similarly, 7, 4 and 8 are given numbers. By using these numbers shall we form the greatest and smallest three digit number.

444, 478, 487, 748, 777, 784, 847, 874 888, and so on

Arrange the given digits from the smallest number to greatest number, we get Ascending order.

478, 487, 748, 784, 847, 874 and so on

Arrange the above from the greatest number to smallest number, we get Descending order.

874, 847, 784, 748, 487,478

888 is the greatest number and 444 is the smallest number.

Practice

1. Form greatest and smallest numbers using the given digits (without repetition of digits)

Number Greatest number Smallest number

2. Complete the following number sequence.

111, 222, 333, 444, 555, 666, 777.

150, 155, 160, 165, 170, 175, 180.

210, 310, 410, 510, 610, 710, 810.

333, 433, 533, 633, 733, 833, 933.

3. Find the numbers.

a. 4 Hundreds; 5 Tens; 0 Ones 450

b. 3 Hundreds; 0 Tens; 1 One 301

c. 5 Hundreds; 8 Tens; 9 Ones 589

d. 8 Hundreds; 5 Ones 805

4. Write the number names.

Numeral : Number name

156 : One Hundred and fifty six

340 : Three Hundred and forty

408 : Four Hundred and Eight

696 : Six Hundred and Ninety six

5. Write the place value for the bubbled digits.

a) 1 9 8   Answer: Hundred

b) 9 0 8   Answer: Ones

c) 5 4 3   Answer: Tens

6. Write down the odd and even numbers seperately.

123 333 422 588 246 535

a. Odd numbers: 123, 333, 535

b. Even numbers: 422, 588, 246

7. write <, >, = in the box.

105 150   Answer: 105 < 150

419 547   Answer: 419 < 547

394 387   Answer: 394 > 387

761 683   Answer: 761 > 683

660 660   Answer: 660 = 660

983 990   Answer: 983 < 990

8. Write the numbers in ascending and descending order.

326 323 301 356 365 399 308 340

Ascending order : 301, 308, 323, 326, 340, 356, 365, 399

Descending order : 399, 365, 356, 340, 326, 323, 308, 301

9. Using the numerals 6, 8 and 5 only once write the greatest and smallest 3 digit number.

Greatest number : 865

Smallest number : 568