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
- Subtraction with and without Regrouping
- Addition and Subtraction Together
- Multiplication
- Multiplication by Tens, Hundreds, Thousands
- Multiplication by a 2-Digit Number
- Multiplication by a 3-Digit Number
- Division
- Division by 10, 100, 1000
- Patterns
Addition with and without Regrouping
(i) Addition without Regrouping
1 5 4 0 3 2
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
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
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
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
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
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
5 7 5 7 7 8
(ii) Addition with Regrouping
3 5 2 9 0 8
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.
3 5 2 9 0 8
4
Step 3: Add the digits in tens place. 1 + 0 + 5 = 6, we write 6 in the tens place of the result.
3 5 2 9 0 8
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.
3 5 2 9 0 8
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.
3 5 2 9 0 8
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.
3 5 2 9 0 8
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.
3 5 2 9 0 8
8 3 2 7 6 4
Subtraction with and without Regrouping
(i) Subtraction without Regrouping
9 5 8 3 4 7
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
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
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
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
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
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
2 3 3 3 3 4
(ii) Subtraction with Regrouping
4 5 2 1 5 3
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 5 2 1
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.
4 5 2
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.
4 5
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
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
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 1 2 2 9 7
Addition and Subtraction Together
7 5 3 0 2 8
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
4 1 7 4 4 6
When addition and subtraction are coming together, start the operations one-by-one from the left.
Multiplication
The numbers that are multiplied are called6 x 4 = 24, here 6 and 4 are
Multiplication by Tens, Hundreds, Thousands
(i) Multiplication by Tens
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
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
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
2 1 2 0 6
(To multiply with 20, we just multiplied with 2 and put a zero to the right)
2 1 2 0 6
8 4 8 2 4
2 1 2 0 6
8 4 8 2 4
Multiplication by a 3-Digit Number
2 5 1 4
(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
1 5 0 8 4
5 0 2 8 0
2 5 1 4
1 5 0 8 4
5 0 2 8 0
Division
6. The symbol of division is
7
(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.
7
6
7
6
6 9
7
6 7
4 0
6 9 5
7
6 7
4 0
5
6 9 5 8
7
6 7
4 0
5 6
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 example10
5 4
4
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.
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.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 |
3 x 37 = 111 |
6 x 37 = 222 |
9 x 37 = 333 |
12 x 37 = 444 |
15 x 37 = 555 |
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 |