Mental Subtraction Strategies - grade 1 Mental Math for Class 1 Math

Subtraction is a process of finding the difference between two or more items together. Mental Subtraction is used to find the difference between large numbers in the simplest way.

This concept introduces mental math strategies for subtraction for students.

In this learning concept, the students will learn to

• Apply the Subtraction tricks
• Use of forward counting and backward counting in subtraction.

Each concept is explained to class 1 maths students with illustrations and examples, and a concept map is given to summarize the idea. At the end of the page, two printable worksheets with solutions are attached for students to practice. Download the worksheets with solutions and assess your knowledge.

What Is Subtraction?

• To find the difference between any numbers.

How to Subtract Mentally?

We will learn some easy methods to do subtraction mentally.

Subtract 1-Digit Number From 1-Digit Number

• Subtraction by Forward Counting

  • Consider the second number (Subtrahend) and count the number of steps forward till getting first number (Minuend).

    Example:

    

    Method:

    
  • In the above example, we start counting from number 5 till getting the number 8.
  • Then count the number of steps that we have counted forward.
    So, we get:
    

• Subtraction by Backward Counting

  • Consider the first number (Minuend) and count the number of steps backwards equal to the second number (Subtrahend).

    Example:

    

    Method:

    
  • In the above example, we start counting backwards from the number 7.
  • We have subtrahend as 3, so we count 3 steps backwards.
  • We reached at number 4. It is our answer.
  • This method will make our subtraction easier.
    So, we get:
    

Subtract 1-Digit Number From 1-Digit Number

• Subtract any 1-digit number from 10 using number bonds of 10.

  • We use here number bonds of 10.

    Example 1:

    

    Method:

    
  • In the above example; we know that, if we add 3 to 7, we get 10. (Number bond of 10: 7 + 3 = 10)
  • So, here 7 is 3 less than 10.
    So, we get:
    

    Example 2:

    

    Method:

  • In the above example; we know that, if we add 8 to 2, we get 10. (Number bond of 10: 2 + 8 = 10)
  • So, here 2 is 8 less than 10.
    So, we get:
    

• Subtraction By Splitting of 2-digit Number Into Tens and Ones

  • Split 2-digit number into Tens and Ones, make subtraction of Ones.

    Example:

    

    Method:

    
  • In the above example, we split 28 into 20 Tens and 8 Ones.
  • Then subtract 5 from 8 Ones. We get 3.
  • Adding 20 Tens and 3 Ones, we get 23.

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