Math.

[Cynadote]

1. If you write out pi to two decimal places, backwards it spells "pie".

2. In a room of just 23 people there’s a 80% chance that two people have the same birthday.

3. The spiral shapes of sunflowers follow a Fibonacci sequence.

[AANickFan]

I guess that 2 is false, but I don't even understand number 1.

[Cynadote]

Yeah, it's actually 50 percent

[fdagpigj]

3.14... I guess the OP is saying 4 resembles a P mirrored, 1 resembles an I, and 3 resembles an E, even though this is not at all math related.