# operations with Natural Numbers

**ADDITION AND SUBTRACTION**

2 + 2 = 4 two plus two equals/is four

6 – 4 = 2 six minus four equals/is two

Bracket use: Remember that you must do the operations in brackets first.

Example:

9 – 1 + 3= 11 9 - (1 + 3) = 9 – 4 = 5

**Addition properties:**

- *Commutative property:*

3 + 5 = 5 + 3

- *Associative property:*

(2 + 3) + 7 = 2 + (3 + 7)

**MULTIPLICATION**

The multiplication is a repeated addition:

35 + 35 + 35 = 3 · 35 = 105 three by thirty-five or three times thirty-five equals one hundred and five

**Multiplication properties:**

· *Commutative property*: 3 · 5 = 5 · 3

· *Associative property*: (2 · 3) · 5 = 2 · (3 · 5)

·* Distributive property:* 3 · (4 + 5) = 3 · 4 + 3 · 5 (7 – 3) · 2 = 7 · 2 – 3 · 2

**DIVISION**

To divide is to distribute in equal parts:

150: 6 = 25 one hundred and fifty divided by six equals twenty-five.

The division is **exact **when the remainder equals zero. When the remainder doesn't equal zero we call it **whole division**.

Remember:

D = d · q + r |

And now, you can play and practise the multiplication and division:

**Exercise**

a) 3 + 5 + 7 - 11 - 2 + 10 =

b) 5 - (3 + 1) + 2 - (8 - 6) + 3 =

c) 25 · 2 · 3 = 150

d) 48 : 12 =

e) 72 : 12 : 3 =

f) Calculate the quotient and remainder of the division: 1482 : 15

Quotient =

Remainder =Licensed under the Creative Commons Attribution Non-commercial Share Alike 3.0 License