Mental Subtraction Strategies Maths Grade 2 | Orchids International
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Mental Math

Mental Subtraction Strategies

What is subtraction?

  • To find the difference between any numbers.

What is mental subtraction?

  • Mental subtraction is the way of solving subtraction problems in your head without using a calculator or without writing any steps.

We will learn some easy subtraction strategies.

G2_1_Mental Sub_Subtraction Tricks


Subtract 2-digit number from 2-digit number

  • Subtraction by columns
    • Imagine both the numbers are one below other. Always hold subtrahend below to the Minuend. Then first subtract the ones place digits, then subtract tens place digits.

    Example:

    G2_2_Mental Sub_Example

    Step 1: In the above example, we hold the number 35 below the number 76 in mind.

    Step 2: Then first we subtract the ones place digits: 6 – 5 = 1.

    This is our ones place digit in the answer.

    Step 3: After that we subtract the tens place digits: 7 – 3 = 4.

    This is our tens place digit in the answer.

    So, the answer is:

    G2_3_Mental Sub_Example Answer

  • Subtraction by parts
    • Break the subtrahend (number that will be subtracted from another number) into Tens and Ones. And then do the subtraction.

    Example:

    G2_4_Mental Sub_Example

    Step 1: In the above example, we split 35 into Tens and Ones as 30 Tens and 5 Ones.

    Step 2: Then first we subtract 30 from 56.

    56 – 30 = 26

    Step 3: Now there is 5 remaining to subtract. So, we subtract 5 from 26.

    26 – 5 = 21

    So, the answer is:

    G2_5_Mental Sub_Example Answer

  • Subtraction by counting forward
    • This strategy will work if two numbers (Minuend and Subtrahend) are close to each other.
    • Think how much you need to add to the Subtrahend (number that will be subtracted) to get the Minuend (number from which another number will be subtracted).

    Example:

    G2_6_Mental Sub_Example

    Step 1: In the above example, we count forward from 86 till we get the number 94. We have 8 steps going forward.

    Step 2: It means we need to add 8 to the number 86 to get 94.

    Step 3: So, if we go backward 8 steps from 94 we got number 86.

    So, the answer is:

    G2_7_Mental Sub_Example Answer

  • Subtraction by using addition
    • Start from smaller number (Subtrahend) add up numbers until get the bigger number (Minuend).

    Example:

    G2_8_Mental Sub_Example

    Step 1: In the above example, first we add 3 to 27 so that we can get the nearest tens number.

    3 + 27 = 30

    Step 2: We added 40 to 30.

    30 + 40 = 70

    Step 3: Then added 2 to 70, we get 72.

    Step 4: So, here we have added 45 to 27, to get the number 72.

    If we subtract 45 from 72, we will get 27.

    So, the answer is:

    G2_9_Mental Sub_Example Answer

  • Subtract an easy number that is close to Subtrahend
    • Subtract the easy number which is close to the subtrahend, and then correct the answer.

    Example:

    G2_10_Mental Sub_Example

    Step 1: In the above example, instead of 49 we have subtracted 50 from 97. 50 is the nearest Tens of the 49, so it is easy to subtract Tens Numbers from the minuend.

    Step 2: After subtracting we get:

    97 - 50 = 47

    Step 3: But here we have subtracted 1 more number from minuend. So, we have to add 1 more number to 47.

    47 + 1 = 48

    So, the answer is:

    G2_11_Mental Sub_Example Answer


Subtract 1-digit numbers from 100

  • Subtraction by parts
    • Divide 100 into two parts as 90 + 10.
    • Then subtract given 1-digit number from 10 and add that answer to 90.

    Example:

    G2_12_Mental Sub_Example

    Step 1: In the above example, we have divided 100 as 90 + 10.

    Step 2: Then subtracted 7 from 10: 10 - 7 = 3

    Step 3: Added 3 to 90: 90 + 3 = 93

    So, the answer is:

    G2_13_Mental Sub_Example Answer


Subtract 2-digit numbers from 100

  • Subtraction by parts
    • Break the number 100 into two parts in such a way that one part is the nearest Tens number of the subtrahend.

    Example:

    G2_14_Mental Sub_Example

    Step 1: In the above example, the nearest tens number from the 34 is 40.

    Step 2: So, we break 100 into two parts as: 60 + 40

    Step 3: Then we subtract: 40 – 34 = 6

    Step 3: Added that 6 to 60.

    So, the answer is:

    G2_15_Mental Sub_Example Answer

New word:

G2_16_Mental Sub_New words

Fun fact:

G2_17_Mental Sub_Fun facts


G2_18_Mental Sub_Mindmap
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