Notes on the Four Basic Operations - JSS1 Mathematics Lesson Note

The four basic operations in mathematics are fundamental for solving various arithmetic problems. These operations are addition, subtraction, multiplication, and division. Understanding these operations using place value helps in grasping the underlying principles of arithmetic.

i. Addition

Definition: Addition is the process of combining two or more numbers to get a total sum.

Example: Adding 237 and 489.

Place Value Alignment: Write the numbers one below the other, aligning the digits according to their place values (units, tens, hundreds, etc.).

237

+ 489

Add from Right to Left: Start adding from the rightmost column (units place).

Units: 7 + 9 = 16 (write 6 in the units place and carry over 1 to the tens place).

Tens: 3 + 8 = 11, plus the carried over 1 = 12 (write 2 in the tens place and carry over 1 to the hundreds place).

Hundreds: 2 + 4 = 6, plus the carried over 1 = 7 (write 7 in the hundreds place).

237

+ 489

-----

726

So, 237 + 489 = 726.

ii. Subtraction

Definition: Subtraction is the process of taking one number away from another to find the difference.

Example: Subtracting 154 from 572.

Place Value Alignment: Write the numbers one below the other, aligning the digits according to their place values.

572

- 154

Subtract from Right to Left: Start subtracting from the rightmost column.

Units: 2 - 4 (Since 2 is less than 4, we need to borrow 1 from the tens place, making it 12 - 4 = 8. Reduce the tens place digit by 1).

Tens: 6 - 5 = 1 (because we borrowed 1, 7 becomes 6).

Hundreds: 5 - 1 = 4.

572

- 154

-----

418

So, 572 - 154 = 418.

iii. Multiplication

Definition: Multiplication is the process of adding a number to itself a certain number of times.

Example: Multiplying 34 by 7.

Place Value Alignment: Write the number to be multiplied (34) and the multiplier (7).

x 7

Multiply Each Digit: Multiply each digit of 34 by 7, starting from the right.

Units: 4 x 7 = 28 (write 8 in the units place and carry over 2 to the tens place).

Tens: 3 x 7 = 21, plus the carried over 2 = 23 (write 3 in the tens place and carry over 2 to the hundreds place, if there were one).

x 7

-----

238

So, 34 x 7 = 238.

iv. Division

Definition: Division is the process of distributing a number into equal parts.

Example: Dividing 825 by 5.

Set Up the Division: Write 825 inside the division bracket and 5 outside.

______

5 | 825

Divide Step-by-Step: Divide each part of the number starting from the leftmost digit.

How many times does 5 go into 8? (1 time, write 1 above the line). 5 x 1 = 5, subtract from 8 to get 3.

1__

5 | 825

-5

Bring down the next digit (2) to make it 32. How many times does 5 go into 32? (6 times, write 6 above the line). 5 x 6 = 30, subtract from 32 to get 2.

16_

5 | 825

-5

-30

Bring down the next digit (5) to make it 25. How many times does 5 go into 25? (5 times, write 5 above the line). 5 x 5 = 25, subtract from 25 to get 0.

165

5 | 825

-5

-30

- 25

So, 825 ÷ 5 = 165.

Summary

Addition involves combining numbers to find a total.

Subtraction involves finding the difference by removing one number from another.

Multiplication involves adding a number to itself a specific number of times.

Division involves distributing a number into equal parts.