# Whole Numbers (Integers)

**Natural Numbers** are the numbers that we use to count: 1, 2, 3, 4, 5, 6, 7, …

We represent all of them by

= {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, …}

When we add number zero and the negative numbers to the Natural Numbers, we obtain the **Whole Numbers** and we represent all of them by:

= {…, -4, -3, -2, -1, 0, 1, 2, 3, …}

and we represent these numbers in a straight line

The **absolute value** of a whole number is the natural number which results when we remove its sign:

|-5| = 5 |11| = 11 |0| = 0

Remember the **hierarchy** of operations:

- Brackets first.

- Powers and roots.

- Multiplication and division.

- Addition and subtraction.

**Exercise**.- Calculate:

a) 7 - 5·(3-4)+ 8:2 =

b) 3- [4 - 5·3 + 12:2 - (4 + 5·3)] =

c) 3·5 - 4 + 2·(5- 3·2) + 8:(4-2) =

d) |-7|=

e) |13|=

Solutions: a) 16; b) 27; c) 13; d) 7; e) 13

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