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Class V

Operations on Large Numbers


In the previous class, we learnt how to add, subtract, multiply and divide numbers. Here we will learn these operations for bigger numbers.

Addition with and without Regrouping

(i) Addition without Regrouping

Add 1,54,032 and 4,21,746

Step 1: Arrange the numbers in columns.
 1 5 4 0 3 2
+ 4 2 1 7 4 6

Step 2: Add the digits in ones place. 2 + 6 = 8, we write 8 in the ones place of the result.
 1 5 4 0 3 2
+ 4 2 1 7 4 6
      8

Step 3: Add the digits in tens place. 3 + 4 = 7, we write 7 in the tens place of the result.
 1 5 4 0 3 2
+ 4 2 1 7 4 6
    7 8

Step 4: Add the digits in hundreds place. 0 + 7 = 7, we write 7 in the hundreds place of the result.
 1 5 4 0 3 2
+ 4 2 1 7 4 6
   7 7 8

Step 5: Add the digits in thousands place. 4 + 1 = 5, we write 5 in the thousands place of the result.
 1 5 4 0 3 2
+ 4 2 1 7 4 6
   5 7 7 8

Step 6: Add the digits in ten-thousands place. 5 + 2 = 7, we write 7 in the ten-thousands place of the result.
 1 5 4 0 3 2
+ 4 2 1 7 4 6
  7 5 7 7 8

Step 7: Add the digits in lakhs place. 1 + 4 = 5, we write 5 in the lakhs place of the result.
 1 5 4 0 3 2
+ 4 2 1 7 4 6
 5 7 5 7 7 8

1,54,032 + 4,21,746 = 5,75,778

(ii) Addition with Regrouping

Add 3,52,908 and 4,79,856

Step 1: Arrange the numbers in columns.
 3 5 2 9 0 8
+ 4 7 9 8 5 6

Step 2: Add the digits in ones place. 8 + 6 = 14, we write 4 in the ones place of the result and 1 in the tens place as a carry over.
    1
 3 5 2 9 0 8
+ 4 7 9 8 5 6
      4

Step 3: Add the digits in tens place. 1 + 0 + 5 = 6, we write 6 in the tens place of the result.
    1
 3 5 2 9 0 8
+ 4 7 9 8 5 6
    6 4

Step 4: Add the digits in hundreds place. 9 + 8 = 17, we write 7 in the hundreds place of the result and 1 in the thousands place as a carry over.
   1
 3 5 2 9 0 8
+ 4 7 9 8 5 6
    7 6 4

Step 5: Add the digits in thousands place. 1 + 2 + 9 = 12, we write 2 in the thousands place of the result and 1 in the ten-thousands place as a carry over.
  1
 3 5 2 9 0 8
+ 4 7 9 8 5 6
   2 7 6 4

Step 6: Add the digits in ten-thousands place. 1 + 5 + 7 = 13, we write 3 in the ten-thousands place of the result and 1 in the lakhs place as a carry over.
1
 3 5 2 9 0 8
+ 4 7 9 8 5 6
  3 2 7 6 4

Step 7: Add the digits in lakhs place. 1 + 3 + 4 = 8, we write 8 in the lakhs place of the result.
1
 3 5 2 9 0 8
+ 4 7 9 8 5 6
 8 3 2 7 6 4

3,52,908 + 4,79,856 = 8,32,764

Subtraction with and without Regrouping

(i) Subtraction without Regrouping

Subtract 7,25,013 from 9,58,347

Step 1: Arrange the numbers in columns.
 9 5 8 3 4 7
- 7 2 5 0 1 3

Step 2: Subtract the digits in ones place. 7 - 3 = 4, we write 4 in the ones place of the result.
 9 5 8 3 4 7
- 7 2 5 0 1 3
     4

Step 3: Subtract the digits in tens place. 4 - 1 = 3, we write 3 in the tens place of the result.
 9 5 8 3 4 7
- 7 2 5 0 1 3
    3 4

Step 4: Subtract the digits in hundreds place. 3 - 0 = 3, we write 3 in the hundreds place of the result.
 9 5 8 3 4 7
- 7 2 5 0 1 3
   3 3 4

Step 5: Subtract the digits in thousands place. 8 - 5 = 3, we write 3 in the thousands place of the result.
 9 5 8 3 4 7
- 7 2 5 0 1 3
   3 3 3 4

Step 6: Subtract the digits in ten-thousands place. 5 - 2 = 3, we write 3 in the ten-thousands place of the result.
 9 5 8 3 4 7
- 7 2 5 0 1 3
  3 3 3 3 4

Step 7: Subtract the digits in lakhs place. 9 - 7 = 2, we write 2 in the lakhs place of the result.
 9 5 8 3 4 7
- 7 2 5 0 1 3
 2 3 3 3 3 4

958347 - 725013 = 233334

(ii) Subtraction with Regrouping

Subtract 2,39,856 from 4,52,153

Step 1: Arrange the numbers in columns.
 4 5 2 1 5 3
- 2 3 9 8 5 6

Step 2: Subtract the digits in ones place. 3 - 6 is not possible, so we regroup the digit in tens place.
5 tens = 4 tens + 10 ones, we add 10 ones to 3 ones. Now the digit at ones place is 13. Now subtract. 13 - 6 = 7, we write 7 in the ones place of the result.
    4 13
 4 5 2 1 5 3
- 2 3 9 8 5 6
     7

Step 3: Subtract the digits in tens place. 4 - 5 is not possible, so we regroup the digit in hundreds place.
1 hundred = 10 tens, we add 10 tens to 4 tens. Now the digit at tens place is 14. Now subtract. 14 - 5 = 9, we write 9 in the tens place of the result.
    0 14
 4 5 2 1 5 3
- 2 3 9 8 5 6
    9 7

Step 4: Subtract the digits in hundreds place. 0 - 8 is not possible, so we regroup the digit in thousands place.
2 thousands = 1 thousands + 10 hundreds, we add 10 hundreds to 0 hundreds. Now the digit at hundreds place is 10. Now subtract. 10 - 8 = 2, we write 2 in the hundreds place of the result.
   1 10
 4 5 2 1 5 3
- 2 3 9 8 5 6
    2 9 7

Step 5: Subtract the digits in thousands place. 1 - 9 is not possible, so we regroup the digit in ten-thousands place.
5 ten-thousands = 4 ten-thousands + 10 thousands, we add 10 thousands to 1 thousands. Now the digit at thousands place is 11. Now subtract. 11 - 9 = 2, we write 2 in the thousands place of the result.
  4 11
 4 5 2 1 5 3
- 2 3 9 8 5 6
   2 2 9 7

Step 6: Subtract the digits in ten-thousands place. 4 - 3 = 1, we write 1 in the ten-thousands place of the result.
   4
 4 5 2 1 5 3
- 2 3 9 8 5 6
  1 2 2 9 7

Step 7: Subtract the digits in lakhs place. 4 - 2 = 2, we write 2 in the lakhs place of the result.
 4 5 2 1 5 3
- 2 3 9 8 5 6
 2 1 2 2 9 7
2,39,856 - 4,52,153 = 2,12,297

Addition and Subtraction Together

Let's find 7,53,028 + 1,81,734 - 5,17,316

Step 1: Find 7,53,028 + 1,81,734.
  7 5 3 0 2 8
+ 1 8 1 7 3 4
  9 3 4 7 6 2

Step 1: Now we subtract 5,17,316 from the sum got in step 1.
  9 3 4 7 6 2
-  5 1 7 3 1 6
  4 1 7 4 4 6

7,53,028 + 1,81,734 - 5,17,316 = 4,17,446
When addition and subtraction are coming together, start the operations one-by-one from the left.

Multiplication

The numbers that are multiplied are called factors and the answer is called the product.
6 x 4 = 24, here 6 and 4 are factors of the product 24.

Multiplication by Tens, Hundreds, Thousands

(i) Multiplication by Tens

To multiply a number by 10, 20, 30... 90, multiply the number by 1, 2, 3... 9 respectively and insert one zero on the right of the product.

5 x 10 = 50
5 x 20 = 100
5 x 30 = 150
5 x 40 = 200
5 x 50 = 250
5 x 60 = 300
5 x 70 = 350
5 x 80 = 400
5 x 90 = 450

(ii) Multiplication by Hundreds

To multiply a number by 100, 200, 300... 900, multiply the number by 1, 2, 3... 9 respectively and insert two zeroes on the right of the product.

8 x 100 = 800
8 x 200 = 1600
8 x 300 = 2400
8 x 400 = 3200
8 x 500 = 4000
8 x 600 = 4800
8 x 700 = 5600
8 x 800 = 6400
8 x 900 = 7200

(iii) Multiplication by Thousands

To multiply a number by 1000, 2000, 3000... 9000, multiply the number by 1, 2, 3... 9 respectively and insert three zeroes on the right of the product.

8 x 1000 = 8000
8 x 2000 = 16000
8 x 3000 = 24000
8 x 4000 = 32000
8 x 5000 = 40000
8 x 6000 = 48000
8 x 7000 = 56000
8 x 8000 = 64000
8 x 9000 = 72000

Multiplication by a 2-Digit Number

Multiply 21,206 by 24

Step 1: Write the numbers as below.
 2 1 2 0 6
x    2 4

Step 2: We know 24 = 20 + 4, We will multiply 21,206 by 4 and 24 separately and write the partial products as below.
(To multiply with 20, we just multiplied with 2 and put a zero to the right)
 2 1 2 0 6
x   2 4
  8 4 8 2 4
4 2 4 1 2 0

Step 3: Add the sub products to get the final product.
 2 1 2 0 6
x   2 4
  8 4 8 2 4
4 2 4 1 2 0
5 0 8 9 4 4

Multiplication by a 3-Digit Number

Multiply 2,514 by 126

Step 1: Write the numbers as below.
 2 5 1 4
x  1 2 6

Step 2: We know 126 = 100 + 20 + 6, We will multiply 21,206 by 6, 20 and 100 separately and write the partial products as below.
(To multiply with 20, we just multiplied with 2 and put a zero to the right.
To multiply with 100, we just put two zeroes to the right.)
  2 5 1 4
x  1 2 6
  1 5 0 8 4
  5 0 2 8 0
2 5 1 4 0 0

Step 3: Add the sub products to get the final product.
  2 5 1 4
x  1 2 6
  1 5 0 8 4
  5 0 2 8 0
2 5 1 4 0 0
3 1 6 7 6 4

Division

Terms associated with Division:
1. Dividend: The number to be divided is called the dividend.
2. Divisor: The number by which we divide the dividend is called the divisor.
3. Quotient: The number that we get after division is called the quotient.
4. Remainder: The number which is left over after division is called the remainder.
5. dividend = divisor x quotient + remainder.
6. The symbol of division is ÷

Divide 4,87,067 by 7.

Step 1: Write the numbers as below.

7  4 8 7 0 6 7

Step 2:
(i) Identify the number that starting from left of the dividend (4,87,067) which is divisible by 7.
4 is not divisible by 7, so we will consider 48.
We know, 7 x 6 = 42 and 7 x 7 = 49,
(ii) so we write 6 in the quatient place and 42 under 48.
(iii) subtract 42 from 48 and write the difference below.

  6
7  4 8 7 0 6 7
  4 2   
  6

Step 3: Bring down the next digit (7). Divide 67 by 7. Continue the steps mentioned in Step 2.

  6 9
7  4 8 7 0 6 7
  4 2 ↓   
  6 7
    6 3  
    4

Step 4:
  6 9 5
7  4 8 7 0 6 7
  4 2 ↓ ↓  
  6 7
    6 3 ↓  
    4 0
   3 5  
    5
Step 5:
  6 9 5 8
7  4 8 7 0 6 7
  4 2 ↓ ↓ ↓  
  6 7 ↓ ↓
    6 3 ↓ ↓  
    4 0
   3 5 ↓  
    5 6
   5 6  
     0
Step 6:
  6 9 5 8 1
7  4 8 7 0 6 7
  4 2 ↓ ↓ ↓ ↓  
  6 7 ↓ ↓ ↓
    6 3 ↓ ↓ ↓  
    4 0 ↓ ↓
   3 5 ↓ ↓  
    5 6
   5 6 ↓  
     0 7
    7  
     0

4,87,067 ÷ 7 = 69,581

Points to remember:
1. Remainder is always less than the divisor.
2. Division by 0 is not possible, it is meaningless.

Division by 10, 100, 1000

See the below example

   2 5
10  2 5 4
  2 0 ↓  
   5 4
    5 0
   4

We can see that, when a number is divided by 10, the quotient is obtained by removing the digit in the ones place of the dividend. and the removed digit is the remainder.

When a number is divided by 100, the quotient is obtained by removing the digits in the ones and tens place of the dividend. The number formed by these removed digits is the remainder.

When a number is divided by 1000, the quotient is obtained by removing the digits in the ones, tens and hundreds place of the dividend. The number formed by these removed digits is the remainder.
Examples:

41,835 ÷ 10 = 4,183 and remainder = 5
47,003 ÷ 100 = 470 and remainder = 3
61,903 ÷ 10 = 6,190 and remainder = 3
61,903 ÷ 100 = 619 and remainder = 3
3,20,008 ÷ 1,000 = 320 and remainder = 8

Patterns

In the previous class, we have learnt the basics of patterns. Let's see some interesting patterns now. Example 1:

1 x 8 + 1 = 9
12 x 8 + 2 = 98
123 x 8 + 3 = 987
1234 x 8 + 4 = 9876
12345 x 8 + 5 = 98765

Example 2:

3 x 37 = 111
6 x 37 = 222
9 x 37 = 333
12 x 37 = 444
15 x 37 = 555

Example 3:

0 x 9 + 1 = 1
1 x 9 + 2 = 11
12 x 9 + 3 = 111
123 x 9 + 4 = 1111
1234 x 9 + 5 = 11111