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# Basic Arithmetic Operations

Module by: ProgressiveQuest. E-mail the author

Summary: Understanding the basic arithmetic operations namely Addition, Subtraction, Multiplication and Division.

### Insight

• Components
• Operation: 2 + 3
• Operator: + (plus)
• Operands: 2 and 3
• Properties
• Commutative: a $b = b$ a
• Associative: (a $b)$ c = a $(b$ c)

### Insight

• Plus
• Sum
• Summation
• Totalling
• Counting
• Properties
• Commutative: a + b = b + a
• Associative: (a + b) + c = a + (b + c)

### Insight

• Minus
• Difference

Properties

• Not Commutative: a - bb - a
• Not Associative: (a - b) - ca - (b - c)

### Insight

• Product
• a X b = a times b's = b + b + b + ... a times
• Properties
• Commutative: a X b = b X a
• Associative: (a X b) X c = a X (b X c)

### Exercises

#### Exercise 1

Why is a X b always equal to b X a?

##### Solution

Visualization: Draw a grid with a rows and b columns and rotate the page 90 degress so that the rows appear as columns and columns appear as rows. Now we have b rows and a columns.

a X b = a times b's = b times a's = b X a.

#### Exercise 2

If a X b = c then why is c ÷ a = b and c ÷ b = a?

##### Solution

Note: a times b's = b times a's = c.

Visualization: Draw a grid with a rows and b columns, or; b rows and a columns.

If we repeatedly take away b's then that can be done a times. Therefore c ÷ b = a.

If we repeatedly take away a's then that can be done b times. Therefore c ÷ a = b.

### Insight

• Sharing or Distributing equally
• Shortcut of repeated subtraction
• a ÷ b denotes b is repeatedly subtracted from a for maximum number of times.
• Components
• Quotient: How much each one will get? How many times a number can be repeatedly subtracted?
• Remainder: How much will remain that can not be distributed?

Properties

• Not Commutative: a ÷ bb ÷ a
• Not Associative: (a ÷ b) ÷ ca ÷ (b ÷ c)

### Exercises

#### Exercise 3

If t chocolates are distributed among n students, how many choclates each student will get?

##### Solution

Visualization: Distributing equally.

Visualization: Repeatedly subtracting n chocolates from t chocolates so that each student gets one.

t ÷ n.

#### Exercise 4

If each student should get n chocolates. How many students will get chocolates if there are t chocolates?

##### Solution

Visualization: Repeatedly subtracting n chocolates from t chocolates because each student should get n chocolates.

t ÷ n.

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