Python has two everyday kinds of number. Integers (int) are whole numbers like 7 or -3. Floats (float) have a decimal point, like 2.5. The kind of a value is called its type, and type(x) tells you what it is.
The operators are +, -, * (times) and / (divide). Dividing with / always gives a float, even when it comes out even: 10 / 2 is 5.0. Brackets work as in maths, and * and / happen before + and -.
print(10 / 2)
print(2 + 3 * 4)
print((2 + 3) * 4)5.0 14 20
Three more come up all the time. // divides and drops the remainder (floor division), % gives just the remainder, and ** is "to the power of". % is handy for checking if a number is even: n % 2 is 0 for even numbers and 1 for odd ones.
print(17 // 5)
print(17 % 5)
print(2 ** 10)3 2 1024
Text and numbers don't mix by themselves: "3" + 4 is an error, because Python won't guess whether you meant 7 or "34". Convert first. int("3") turns text into a whole number, float("2.5") into a decimal, and str(4) turns a number into text. + on two strings joins them.
print(int("3") + 4)
print("3" + str(4))7 34
What does this print?
print(9 / 3)| + - * / | Add, subtract, multiply, divide (/ gives a float). |
|---|---|
| // | Floor division: 17 // 5 is 3. |
| % | Remainder: 17 % 5 is 2. n % 2 == 0 means n is even. |
| ** | Power: 2 ** 3 is 8. |
| int() float() str() | Convert a value to a whole number, a decimal or text. |