## 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, floats, etc.) returns a string of that number.

``````    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 `**`.

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``