## Variables

Here's code from a previous section that uses variables:
```# Gets the user's name and greets them
my_name = "Jason"
user_name = input("Enter your name: ")
print(f"Hello {user_name}, nice to meet you. I am {my_name}.\n")

# Gets the user's age and compares
my_age = 31
user_age = input("Enter your age: ")
difference = my_age - int(user_age)
print(f"I am {difference} years older than you.")
```
On the first line, "Jason" is saved in a variable. A variable stores a value to be used later in the program. The value can have one of several different data types. Examples of data types are:
• strings - words or sentences wrapped in quotes like `"hello"`
• integers - whole numbers like `1` or `-76`
• floats - decimal numbers like `1.5` or `0.006`
To create a variable, give it a name, and set it equal to a value using the `=` operator. Variable names can contain only letters, numbers, and the underscore symbol, and the first character cannot be a number. So `variable223` and `new_value1` are valid variable names, but `1num` and `v@r` are not. Variables should be all lowercase, and words should be separated by underscores. This is called snake case.
To inject a variable in a string, use an f-string. The line `print(f"Hello {user_name}, nice to meet you. I am {my_name}.\n")` in the code is an example of an f-string. Put the letter `f` in front of the quotes, and wrap variables in curly brackets.

### Exercise 1 of 9

Which of these are all Python data types?

### Exercise 2 of 9

What data type is the variable x?
```x = "hello"
```

### Exercise 3 of 9

What data type is the variable y?
```y = -4.6
```

### Exercise 4 of 9

What data type is the variable z?
```z = 187
```

### Exercise 5 of 9

Which of these is an acceptable variable name?

### Exercise 6 of 9

Correct the mistake in the line of code.
```my var = 12
```

### Exercise 7 of 9

Which of these is NOT true about variable names?

### Exercise 8 of 9

Write a line of code to print a sentence using the variable name.
```name = "Jessica"
```

```age = 12