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In this lesson, we are going to look at the different `operators`

that ruby contains and how to use them in the `expressions`

.

`+`

symbol is used. It is both binary and unary operator. As the name suggests a `Binary operator`

needs two operands/values on the either side of the operator to perform an operation and a unary operator needs just a single operand. Unary Plus serves no purpose, it is present just for the symmetry with unary minus.

For example : 1+2//binary additionvalue = +3//unary plus

`-`

symbol is used. You can use unary minus to reverse sign of a variable.

For Example : 23.2-2.2//binary subtractionvalue = -3//unary minus

`*`

symbol is used. Perfoms Multiplication on two numeric operands.

For Example : 122*3.14

`/`

symbol is used. Returns result of devision of the first numeric operand by second operand.

For Example : 18/3

Returns remainder after division.

For Example : 13%2//returns 1

If you want to raise `x`

to the power of `y`

(i.e) `x ^ y`

.

It is done by x**y

2 raised to the power 4 returns 16.

`Operators`

have some order of `precedence`

which determines the order in which an expression will be evaluated.

Consider this example,1 + 2 * 3

We might think that the **1 + 2** is performed and the result **3** will be multiplied by **3** and gives **9**. But the **multiplication**, **division** and **exponential** operator have higher precedence than **addition** and **subtraction** operators. Therefore, **2 *3** is performed first and the result is added to **1** and gives **7** as an answer.

However, we can modify the order of precedence by putting a subexpression in parentheses. In the expression **1 + 2 * 3**, if **1 + 2** need to be performed first, put that expression in parentheses.

(1 + 2) * 3this expression produces 9

`Relational operators`

are used for comparisons. They return `Boolean values`

. We compare two values whether they are equal, not equal, less than, greater than, less than or equal to and greater than or equal to.

`==`

sign is used. Used to check whether two numbers are equal or not.

1 == 1returns true because1is equal to1.

`<`

- Less than

`>`

- Greater than

`<=`

- Less than or equal to

`>=`

- Greater than or equal to

**Less than operator** checks whether a number is less than the another number, if **yes** it returns **true** else returns **false**. **Less than or equal to operator** checks whether a number is less than to another number and also checks whether a number is equal to another number, if any one of the condition is correct it returns true else returns false. **Greater than and Greater than or equal to** does the same and checks whether it is **greater**.

Another way to compare two values is using **General comparison** operator. It returns **0(zero)**, **-1** or **+1** depending on the operands. If both the values are equal it returns **zero**, if the first operand is less than the second operand it returns **-1** and **+1** if the first operand is greater than the second.

The General Comparison operator is<=>(< = >).

`Relational operators`

can be used with strings also.

If it is same it returns true. You could see that it returns false for the operation **'Apple' == 'apple'** This is because Ruby is case-sensitive and one of the word has `Uppercase A`

while the other word has `lowercase a`

. We can also use **General comparison operator** with strings.

When comparing **'car'** and **'car'** it returned **0** since both are equal. When comparing **'cab'** with **'car'** it returned **-1** because the 3rd letter of the word **'b'** in **'cab'** is less than **'r'** in **'car'**.

`Logical operators`

allow you to combine two or more relational expressions and returns `Boolean`

value.

**AND operator:**

It returns true when all of the expressions are true and returns false if even one of the expression evaluates to false. You could use this operator using `and`

or `&&`

.

It returned true for the expression **salary == 10 && hours == 40** because we've initialized the value of the variables salary and hours as 10 and 40. It will return false for all other cases.

**OR operator:**

`OR`

operator returns true when any one condition/expression is true and returns false only when all of them are false. You can use this operator using `or`

(or) `||`

You can see that even when only one expression is true **OR** operator returned true.

**NOT operator:**

`NOT`

operator negates a relational expression. You can use `not`

(or) `!`

for this operator.

In the first expression it returned false because the expression **salary == 10** returns true and the not operator negates true and returns false. Likewise, the expression **salary < 10** returns false and not operator negates and returns true.