Flip a Coin in PHP
First we get the number of seconds in the current time on the server. This server's time was 8:20:29 am when you opened this page (the 29 is the number of seconds).
$now_seconds = date("s");
All we do next is check to see if the number is even or odd.
if(($now_seconds  (2 * floor($now_seconds/2))) == 0)
{
// the number is even
}
else
{
// the number is odd
}
That's it. Here's a demonstration example:
$now_seconds = date("s");
if(($now_seconds  (2 * floor($now_seconds/2))) == 0)
{
echo $now_seconds . " is an even number";
}
else
{
echo $now_seconds . " is an odd number";
}
Here's the result:
Reload the page to see the result change.
Flip a 3sided coin
If you want to make a choice between 3 options, you need a threesided coin. Here's a working example script of how to do it in PHP:
$now_seconds = date("s");
if($now_seconds == 0) { $now_seconds = 60; }
if(($now_seconds  (3 * floor($now_seconds/3))) == 0)
{
echo $now_seconds . " is divisible by 3";
}
elseif(($now_seconds  (2 * floor($now_seconds/2))) == 0)
{
echo $now_seconds . " is an even number (and not divisible by 3)";
}
else
{
echo $now_seconds . " is an odd number (and not divisible by 3)";
}
Here's the result:
29 is an odd number (and not divisible by 3)
Reload the page to see the result change.
Here are the complete sets of numbers:
 Column 3 holds the 20 numbers between 1 and 60 that are divisible by 3.
 Column 2 holds the remaining 20 numbers that are even and not divisible by 3.
 And column 1 holds the remaining 20 odd numbers not divisible by 3.
3  2  1 
 3
 6
 9
 12
 15
 18
 21
 24
 27
 30
 33
 36
 39
 42
 45
 48
 51
 54
 57
 60

 2
 4
 8
 10
 14
 16
 20
 22
 26
 28
 32
 34
 38
 40
 44
 46
 50
 52
 56
 58

 1
 5
 7
 11
 13
 17
 19
 23
 25
 29
 31
 35
 37
 41
 43
 47
 49
 53
 55
 59
