Once you have a few variables you can make operations with them:

$base = 20;$height = 10;

$area =$base * $height;  The * I used to multiply$base per $height is the multiplication operator. We have quite a few operators, let’s do a quick roundup of the main ones. To start with, here are the arithmetic operators: +, -, *, / (division), % (remainder) and ** (exponential) We have the assignment operator =, which we already used to assign a value to a variable. Next up we have comparison operators, like <, >, <=, >=. Those work like they do in math. 2 < 1; //false 1 <= 1; // true 1 <= 2; // true  == returns true if the two operands are equal. === returns true if the two operands are identical. What’s the difference? You’ll find it with experience, but for example 1 == '1'; //true 1 === '1'; //false  We also have != to detect if operands are not equal: 1 != 1; //false 1 != '1'; //false 1 != 2; //true //hint: <> works in the same way as !=, 1 <> 1  and !== to detect if operands are not identical: 1 !== 1; //false 1 !== '1'; //true  Logical operators work with boolean values: // Logical AND with && or "and" true && true; //true true && false; //false false && true; //false false && false; //false true and true; //true true and false; //false false and true; //false false and false; //false // Logical OR with || or "or" true || true; // true true || false //true false || true //true false || false //false true or true; // true true or false //true false or true //true false or false //false // Logical XOR (one of the two is true, but not both) true xor true; // false true xor false //true false xor true //true false xor false //false  We also have the not operator: $test = true

!$test //false  I used the boolean values true and false here, but in practice you’ll use expressions that evaluate to either true or false, for example: 1 > 2 || 2 > 1; //true 1 !== 2 && 2 > 2; //false  All of the operators listed above are binary, meaning they involve 2 operands. PHP also has 2 unary operators: ++ and --: $age = 20;
$age++; //age is now 21$age--;
//age is now 20