Operators & Expressions

Doing Things With Values

Storing values in variables is useful. But a program that only stores things and never acts on them isn't much of a program.

An operator is a symbol that performs an action on one or more values. You already know the basic ones from mathematics. Python uses most of them the same way — with a few important additions and one small surprise.

Arithmetic Operators

Run this and look carefully at the last line. 10 / 3 gives 3.3333... — a float. In Python, division always produces a float, even when the numbers divide evenly:

The answer is 5.0, not 5. The division operator / insists on returning a decimal result. If you want a whole number, Python gives you a different operator for that.

Floor Division and Remainder

Two operators that beginners often haven't seen before:

10 // 3 is 3 — how many whole times does 3 fit into 10? 10 % 3 is 1 — what's left over after those 3 fits?

These two operators appear everywhere in real programs. % in particular is one of the most useful tools you'll reach for regularly.

Exponentiation

Raising a number to a power uses **:

Two asterisks, not one. * is multiplication. ** is power.

Order of Operations

Python follows the same precedence rules you learned in school: multiplication and division before addition and subtraction. When in doubt, use parentheses — they always take priority, and they also make your code easier to read.

If you are unsure about precedence, add parentheses. There is no penalty for being explicit, and future-you will be grateful.

String Operators

Operators aren't only for numbers. Two of them work on strings too.

Joining strings with +

+ with strings means join them together. This is called concatenation. Notice the space " " in the middle — strings are joined exactly as given, no spaces added automatically.

Repeating strings with *

* with a string and a number repeats the string that many times. Simple, but surprisingly handy.

Comparison Operators

Sometimes you don't want to calculate a result — you want to ask a question. Comparison operators do this. They always return a boolean: True or False.

The equality check is == — two equals signs. This is one of the most common mistakes for new programmers: writing = when you mean ==. Remember: = stores a value. == asks a question.

Combining Conditions

You can join multiple comparisons together using logical operators.

• and — the whole expression is True only if both sides are True
• or — the whole expression is True if at least one side is True
• not — flips the boolean: True becomes False, False becomes True

These three words — and, or, not — are the building blocks of every decision a program makes. You'll use them constantly.

Expressions vs Statements

A quick distinction worth knowing now:

An expression is any piece of code that produces a value. 3 + 4 is an expression — it produces 7. age > 18 is an expression — it produces True or False. "Hi" * 3 is an expression — it produces "HiHiHi".

A statement is a complete instruction. print("hello") is a statement. name = "Priya" is a statement.

You'll often find expressions inside statements:

result = (price * quantity) + shipping

The right side is one big expression. Python evaluates it completely, then the assignment statement stores the result. This layering — expressions inside statements — is how all real programs are built.

Putting It Together

Read through this slowly. Every line uses something from this lesson or the previous one. There's no new concept here — just the existing ones working together. This is how programming always grows: small things combining into bigger things.

What You Have Learned

Operators let you act on values — calculate, combine, and compare.

The key ideas:

• Arithmetic: +, -, *, /, //, %, ** — each has a precise meaning
• / always returns a float; // returns a whole number
• + and * work on strings too — joining and repeating
• Comparison operators (==, !=, >, <, >=, <=) return True or False
• == asks a question; = stores a value — they are completely different
• and, or, not combine boolean values logically
• An expression produces a value; a statement is a complete instruction