Operations on Numbers

Subtraction

We use subtraction to find the difference between numbers or when we take out/away some objects and want to find out remaining objects.

Example:

Suppose we have 5 mangoes, and we cut and eat 3 mangoes. To find the number of remaining mangoes, we need to do subtraction.

• In subtraction, we take away part of some amount.
• In subtraction, we subtract the smaller number from the bigger one.
• We subtract numbers using the symbol ‘-’, called ‘minus’.

Representation:

• We do subtraction horizontally as well as vertically.
• The larger number is called the minuend.
• The smaller number is called the subtrahend.
• The resultant number is called the Difference.

Read as: 9 minus 5 is equal to 4.

Subtraction of one-digit numbers

We can do subtraction in so many ways.

1. By using fingers


We can use our hand fingers to do the subtraction. Let’s see.



Nisha has eight chocolates. She gives 3 chocolates to Sameer. Now, we need to find Nisha’s remaining number of chocolates.

First method:

Step 1: For eight chocolates open eight fingers.



Step 2: To subtract three chocolates close three fingers from the open fingers.



Step 3: Now count all the open fingers together.



So, we got the number 5.

Nisha has 5 chocolates remaining.



Second method:

For subtracting 3 from 8, count the numbers after the number 3 to the number 8 and open the fingers as well.



We got 5 fingers. So, the correct answer is 5 chocolates.

2. By using counters

Counters: In this method, we draw counters to represent numbers. Each counter (object or shape) represents a number.

Example:

Question: 4-1= ?

Answer:

Step 1: For the number 4 draw four circles.



Step 2: To subtract 1 cross the one circle.



Now, count the remaining circles.



There are 3 circles remaining.

So, the correct answer is

4-1= 3

3. By using a number line

Number line: A straight line on which numbers are placed at the same distance and in the correct order. Numbers are placed from left to right.



We can do subtraction by using number line.

Example:

Question: 10-6= ?

Answer:Draw a line and mark the numbers to 10 or more.



Now, to subtract 6 from 10, move six steps backward to the left side from 10.



You will reach at 4. So, the correct answer is:

10-6= 4

4. Do mentally

We can do subtraction by counting mentally.

Example:

Question: 7-3= ?

Answer:Think about the number 7. Count 3 steps backward from 7. You will get 4.



So, 7 – 3 = 4.

Subtraction Facts

1. When we subtract 0 from a number, the answer is the number itself.

1 – 0 = 1, 5 – 0 = 5, 9 – 0 = 9

2. When we subtract 1 from a number, the answer is the number that comes just before the minuend.

5 -1 = 4, 7 – 1 = 6, 9 – 1 =

Missing numerals in subtraction:

Type 1:

Here, we can take any two numbers whose difference is 5.

6-1=5

7-2=5

8-3=5

There are so many possible answers for this question.

Type 2:

Here, we need to find the number which difference from 2 is 3.

Add the numbers 2 and 3.

2+3=5

So, the correct answer is:

Word Problems

Step 1: Identify the numbers in the word problem which need to be subtracted.

Step 2: Write the word problem in the form of subtraction sentence.

Step 3: Do the subtraction and find out the difference.

Question: 7 sparrows were sitting on a tree. 6 sparrows flew away. How many sparrows were now sitting on the tree?

Answer: The numbers to be subtracted are 7 and 6.

Therefore, only 1 sparrow sitting on the tree.