The sentence "May I draw a round perimeter?"
is a mnemonic for remembering the first six
digits of pi: Count the number of letters in
each word and you get 3.14159.  Each of the
following phrases is also a mnemonic for pi.
Can you figure out how each mnemonic stands
for 3.14159?  Hint: Consider the spelling,
sound, and shapes of the words. 

1. We won your fun drive sign. 
2. Circles and diameters are equally important. 
3. The easy vowels echo mathematical magnitude. 
4. Bring in your initial six equations.

Solutions 1. Each word rhymes with a digit in pi: We rhymes    with three, won rhymes with one, your rhymes    with four, and so on. 2. Each word starts with a letter whose position    in the alphabet is a digit of pi: Cirlces    starts with the third letter of the alphabet,

3. The position of the letter E in each word corresponds to the
   digit of pi: E is the third letter of the, the first letter
   of easy, the fourth letter of vowels, and so on.

4. The first letter of each word has a shape similar to the
   corresponding digit: The first letter of Bring looks like a
   3, the first letter of in looks like a 1, the first letter
   of your looks like a 4, and so on.

Incidentally, the world record for the most digits of pi memorized is now over 40,000 digits.  The record holder used very sophisticated mnemonics to perform that feat.