Good eye. Python has two number types. An integer (int) is a whole number with no decimal point. A float is a number with a decimal point. They look similar, but they behave differently in ways that matter when you're processing real data:

type(5)      # <class 'int'>
type(5.0)    # <class 'float'>
type(-3)     # <class 'int'>
type(0.1)    # <class 'float'>

The type() function tells you exactly what kind of value you're dealing with. Think of it like checking a cell's format in your spreadsheet — is it a whole number or a decimal?

Division is the big one. Regular division with / always returns a float, even if the result is a whole number. This catches people off guard:

10 / 2       # 5.0 (float, not int!)
10 / 3       # 3.3333333333333335
10 // 3      # 3 (integer division — rounds down)
10 % 3       # 1 (modulo — the remainder)

The // operator is floor division — it divides and drops the decimal. The % operator gives you the remainder. These two are a powerful pair: // tells you how many times something fits, % tells you what's left over.

Here's a real example. Say you're tracking time for a project report:

minutes = 137
hours = minutes // 60     # 2
leftover = minutes % 60   # 17
print(f"{hours}h {leftover}m")  # "2h 17m"

You've probably done this math in your head before — "137 minutes, that's 2 hours and 17 minutes." Now Python does it for you.

Yes — use int() and float() to convert explicitly:

int(7.9)      # 7 — truncates, does NOT round
int(7.1)      # 7
float(5)      # 5.0
round(7.9)    # 8 — this one rounds properly
round(3.14159, 2)  # 3.14 — round to 2 decimal places

Notice that int() chops off the decimal — it always moves toward zero. If you want proper rounding (like you'd expect from a spreadsheet's ROUND function), use round() instead.

That's actually a great analogy. None is Python's way of saying "nothing" or "no value." It's not zero, not an empty string — it's the absence of a value entirely. Just like how an empty cell in your spreadsheet isn't the same as a cell containing 0:

type(None)          # <class 'NoneType'>
result = None
print(result)       # None
result is None      # True
result == 0         # False — None is not zero

Functions that don't explicitly return something return None. You'll see it used as a default value or a placeholder for "not yet computed" — like marking a cell as "pending" in your tracking sheet.

Use isinstance(). It's more flexible than type() because it also works with inheritance (you'll learn about that later):

isinstance(5, int)        # True
isinstance(5.0, float)    # True
isinstance(5, (int, float))  # True — checks multiple types
isinstance("5", int)      # False — it's a string, not an int

This is what you'd use in real code. Think of it as data validation — the same way you'd set up a validation rule in your spreadsheet to make sure a column only contains numbers.