# Python Tutorial 3: Basic Operation

## 1. Quick Math

Remember first learning about Maths in primary school? It is similar in Python.

Commonly used operators:

Symbol | Meaning |
---|---|

+ | Addition |

– | Subtraction |

* | Multiplication |

/ | Division |

** | Exponential |

% | Modulus (returns the remainder) |

```
a = 2
b = 2
```

```
sumofAB = a+b
print(sumofAB)
```

```
c = 1
minusC = sumofAB - c
print(minusC)
```

```
multiplyAB = a * b
print(multiplyAB)
```

```
divide = a / b
print(divide)
```

```
exponential = a ** b
print(exponential)
```

```
WhatIsTheReminder = b % a
print(WhatIsTheReminder)
```

## 2. String Operations

The ‘+’ operator behaves differently when it comes to strings. Instead of ‘addition’, we call this ‘concatenation’.

```
c = "2"
d = "3"
```

```
print(c + d)
```

```
x = "Hello"
y = "World!"
print(x + " " + y)
```

If we had concatenated x and y without adding the white space in between the following will be the result:

```
print(x + y)
```

### Concatenating strings with integers

We cannot concatenate strings with integers. To do so we need to convert the integer to a string, using the function str().

```
e = 23
print(c + d + str(e))
```

Similarly, in order to add a string (which is a number) to an integer, we can also convert the string to an integer using int().

```
print(int(c) + int(d) + e)
```

# Try it out!

Assign 100 to principal, 1.05 to rate and calculate the product. Then, concatenate the output with “At the end of the year, I would have $” and print the result.

```
principal = 100
rate = 1.05
print("At the end of the year, I would have $" + str(principal*rate))
```

# 3. Logical operators

In the previous chapter we covered some of the commonly used logical operators, which will return either True or False.

Here are more logical operators.

### Equal to? Not Equal to?

‘!=’ is the opposite of ‘==’. It means not equal to.

```
x = 6
print(x != 6)
```

```
print(x != 8)
```

### Is something inside a string?

We can find out whether a substring is present in another string using the ‘in’ operator. While this may sound redundant for now, it is useful to find whether a certain element is present in a list. You will more about lists in the next chapter.

```
a = 'at'
b = 'bat'
c = 'bath'
```

```
print(a in b)
```

```
print(b in c)
```

```
print(c in a)
```

Putting ‘not’ in the boolean expression will return the opposite output.

```
print(a not in b)
```

```
print(b not in c)
```

```
print(c not in a)
```