Subtraction

**Category : **3rd Class

**LEARNING OBJECTIVES**

**This lesson will help you to:**

- Understand the concept of subtraction using a 10 x 10 grid.
- Subtract using 2 digit numbers.
- Subtract using 3 digit numbers.
- Apply subtraction to real life situations.

**Real life Examples**

- Elevator is a real life example of addition and subtraction. The ground floor is considered to be 0.
- Subtraction helps in calculating the amount left in bank account after debits.

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**AMAZING FACTS**

- Subtract is formed by two words “sub” and “tract”. “Sub” means “below” and “tract” means “to pull away”.
- When we subtract zero from a particular number (or digit of a number) we get the number (or the digit) itself. For example: 413-100=313

**QUICK CONCEPT REVIEW**

Subtraction is taking away a certain number of objects from a bigger set of objects.

**MORE ABOUT SUBRTACTION**

- Subtraction is one of the basic four operations.
- It is denoted by the symbol “-“. For example: 12 subtracted from 45 can be written as 45-12.
- The number of items left after subtraction is called “difference”.
- A 10 x 10 number grid is a helpful tool to subtract 2-digit numbers.
- Some words that denote addition are "minus", "take away" and "left",
- Addition can be done in different ways
- Counting in tens:
__47- 34__=__47 - 10 -10-10-4__ - Place value: 56 - 13

6 – 3 = 3

50 - 10 = 40

40 + 3 = 43

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**HISTORICAL PREVIESW**

- The plus and minus symbols were in use before they appeared in print. For example, they were painted on barrels to indicate whether or not the barrels were full.
- To make subtraction easier it is important to regroup the numbers.

**For example**: 781 - 676

Subtract the ones = 11 - 6 = 5

Subtract the tens = 70-70=0

Subtract the hundreds = 700 - 600 = 100

100 + 5 = 105

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**MISCONCEPT/CONCEPT**

**Misconcept:**Subtraction is commutative.**Concept:**Subtraction is not commutative. For**example:**

18-13 is not equal to 13-18

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**PLAY TIME:**

- Pick up a 3 digit number. Mix the digits of the number and form a new 3-digit number. Subtract the smaller number from the bigger number.

*play_arrow*Subtraction*play_arrow*Introduction*play_arrow*Problems Based on Addition and Subtraction

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