Subtraction | Mathematics Olympiad for Class 1 PDF Download

Introduction to Subtraction

We can determine the remaining number of chocolates using a mathematical operation known as Subtraction.

Subtraction can be done in different ways. Let’s discuss in detail

Example of Subtraction

What is Subtraction?

Subtraction is a mathematical operation to remove a number from another number.

• When two numbers are subtracted we get a new number and this number is known as the difference of two numbers.
• Subtraction is the reverse of addition.
• The symbol for subtraction is ‘—’. This is known as ‘minus’ sign.

Example: While subtracting 3 from 5 we write it as 5 – 3 and read as 5 minus 3.

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How to Subtract one-digit and two-digit numbers?

The difference of two numbers can be done using different methods. Different methods of subtraction are discussed below :

1. Vertical Subtraction

• For subtracting two numbers rearrange the numbers in columns. Write the smaller number below the greater number by placing their digits in correct columns ,that is, in ones and tens columns. Subtract one column at a time.
• Start subtracting from the ones column and then move towards the left to subtract digits in the tens column.

Examples:

•  Take away 4 from 7
  So, 7 – 4 = 3
• Find the difference of 18 and 7
  So, 18 – 7 = 11
• In a shop 48 mobiles are placed on a table. If 15 mobiles are sold out, what is the remaining number of mobiles in the shop ?
  So, 48 – 15 = 33

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2. Subtraction using number line

Examples: (i) When 8 is removed from 9, what is the result ?

Start from 9 and jump 8 units to the left. You reach at 1.

So, 9 – 8 = 1

(ii) From a bag having 48 marbles pieces, 7 pieces are removed. How many pieces are left in the bag ?

Start from 48 and jump 7 units to the left. You reach at 41.

So, 48 – 7 = 41

3. Subtraction of zero

When 0 is subtracted from any number we get the number itself.

Examples:

1 – 0 = 1
22 – 0 = 22

4. Subtraction of one

When 1 is subtracted from any number, we get the number just before it.

Examples: 2 – 1 = 1
15 – 1 = 14

5. Subtraction by backward counting

Start from 10 and count 4 numbers backwards.

So, 10 – 4= 6

6. Subtraction by striking out

Examples: (i) When 6 shapes are removed from 8 shapes, how many shapes will be left ?

(ii) A box is filled with 8 stars. If 3 stars are removed, how many stars will be left in the box ?

Examples on Each Subtraction Method

1. Subtraction by Striking Out

 Example: There are 7 flowers. If 3 flowers are removed, how many are left?

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2. Subtraction by Backward Counting

Example: A girl has 5 candies. She gives 2 to her friend. How many candies are left?

3. Subtraction of Zero

Example: A box contains 8 pencils. If no pencil is removed, how many pencils are left?
Solution:
8−0=8
Answer: There are 8 pencils left.

4. Subtraction of One

Example: There are 6 books on a shelf. If 1 book is taken away, how many books are left?

Solution:
6 −1 = 5
Answer: There are 5 books left.

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5. Vertical Subtraction

Example: Subtract 12 from 25.

• Subtract the ones column: $5-2=3$
• Subtract the tens column: $2-1=12\; -\; 1\; =\; 1$

Answer: $25-12=1325\; -\; 12\; =\; 13$

6. Subtraction Using a Number Line

Example: Subtract 6 from 10 using a number line.
Solution:

• Start at 10 on the number line and jump 6 spaces to the left.
• $10\; \to \; 9\; \to \; 8\; \to \; 7\; \to \; 6\; \to \; 5\; \to \; 4\backslash text\{10\; \to \; 9\; \to \; 8\; \to \; 7\; \to \; 6\; \to \; 5\; \to \; 4$10 → 9 → 8 → 7 → 6 → 5 → 4
• You land on 4.
  Answer: $10-6=4$

Solved Statement Problems on Subtraction

Example 1
Ram has 6 apples. He eats 2 apples. How many apples are left with him?
Solution:
$6-2=46\; -\; 2\; =\; 4$
Ram has 4 apples left.

Example 2
There are 10 balloons, and 3 of them burst. How many balloons are still there?
Solution:
$10-3=710\; -\; 3\; =\; 7$
There are 7 balloons left.

Example 3
Sita has 15 candies. She gives 5 to her friends. How many candies does she have now?
Solution:
$15-5=1015\; -\; 5\; =\; 10$
Sita has 10 candies left.

Example 4
A basket has 9 oranges. If 4 oranges are taken out, how many are left?
Solution:
$9-4=59\; -\; 4\; =\; 5$
There are 5 oranges left in the basket.

Example 5
In a garden, there are 12 flowers. A gardener plucks 6 flowers. How many flowers are left in the garden?
Solution:
$12-6=612\; -\; 6\; =\; 6$
There are 6 flowers left in the garden.$10\; -\; 6\; =\; 4$