# Python as a Calculator

### Arithmetic Operators

 Operator Operation Expression English description Result `+` addition `11 + 56` 11 plus 56 67 `-` subtraction `23 - 52` 23 minus 52 -29 `*` multiplication `4 * 5` 4 multiplied by 5 20 `**` exponentiation `2 ** 5` 2 to the power of 5 32 `/` division `9 / 2` 9 divided by 2 4.5 `//` integer division `9 // 2` 9 divided by 2 4 `%` modulo (remainder) `9 % 2` 9 mod 2 1

### Types `int` and `float`

type is a set of values and operations that can be performed on those values.

Two of Python's numeric types:

• `int`: integer
For example: `3``4``894``0``-3``-18`

• `float`: floating point number (an approximation to a real number)
For example: `5.6``7.342``53452.0``0.0``-89.34``-9.5`

### Arithmetic Operator Precedence

When multiple operators are combined in a single expression, the operations are evaluated in order of precedence.

 Operator Precedence ** highest - (negation) *, /, //, % + (addition), - (subtraction) lowest

### Syntax and Semantics

Syntax: the rules that describe valid combinations of Python symbols

Semantics: the meaning of a combination of Python symbols is the meaning of an instruction — what a particular combination of symbols does when you execute it.

### Errors

A syntax error occurs when we an instruction with invalid syntax is executed. For example:

```>>> 3) + 2 * 4
SyntaxError: invalid syntax
```

A semantic error occurs when an instruction with invalid semantics is executed. For example:

```>>> 89.4 / 0
Traceback (most recent call last):
File "", line 1, in
89.4 / 0
ZeroDivisionError: float division by zero```