## Number methods in Ruby

Ruby provides a variety of built-in methods you may use on numbers. The following is an incomplete list of integer and float methods.

### Even:

Use `.even?`

to check whether or not an ** integer** is even. Returns a

`true`

or `false`

**.**

**boolean**```
15.even? #=> false
4.even? #=> true
```

### Odd:

Use `.odd?`

to check whether or not an ** integer** is odd. Returns a

`true`

or `false`

**.**

**boolean**```
15.odd? #=> true
4.odd? #=> false
```

### Ceil:

The `.ceil`

method rounds **floats**** up** to the nearest number. Returns an

**.**

**integer**```
8.3.ceil #=> 9
6.7.ceil #=> 7
```

### Floor:

The `.floor`

method rounds **floats**** down** to the nearest number. Returns an

**.**

**integer**```
8.3.floor #=> 8
6.7.floor #=> 6
```

### Next:

Use `.next`

to return the next consecutive ** integer**.

```
15.next #=> 16
2.next #=> 3
-4.next #=> -3
```

### Pred:

Use `.pred`

to return the previous consecutive ** integer**.

```
15.pred #=> 14
2.pred #=> 1
(-4).pred #=> -5
```

### To String:

Using `.to_s`

on a number (** integer**,

**, etc.) returns a string of that number.**

**floats**```
15.to_s #=> "15"
3.4.to_s #=> "3.4"
```

### Greatest Common Denominator:

The `.gcd`

method provides the greatest common divisor (always positive) of two numbers. Returns an ** integer**.

```
15.gcd(5) #=> 5
3.gcd(-7) #=> 1
```

### Round:

Use `.round`

to return a rounded ** integer** or

**.**

**float**```
1.round #=> 1
1.round(2) #=> 1.0
15.round(-1) #=> 20
```

### Times:

Use `.times`

to iterate the given block `int`

times.

```
5.times do |i|
print i, " "
end
#=> 0 1 2 3 4
```

## Math operations in Ruby

In Ruby you can perform all standard math operations on numbers, including: addition `+`

, subtraction `-`

, multiplication `*`

, division `/`

, find remainders `%`

, and work with exponents `**`

.

### Addition:

Numbers can be added together using the `+`

operator.

`15 + 25 #=> 40`

### Subtraction:

Numbers can be subtracted from one another using the `-`

operator.

`25 - 15 #=> 10`

### Multiplication:

Numbers can be multiplied together using the `*`

operator.

`10 * 5 #=> 50`

### Division:

Numbers can be divided by one another using the `/`

operator.

`10 / 5 #=> 2`

### Remainders:

Remainders can be found using the modulus `%`

operator.

`10 % 3 #=> 1 # because the remainder of 10/3 is 1`

### Exponents:

Exponents can be calculated using the `**`

operator.

`2 ** 3 #=> 8 # because 2 to the third power, or 2 * 2 * 2 = 8`