There are many ways to memorize Pi. Some work better for some people and bad for others. Find one that fits you!
1. Groups of 3 or 4
One easy way to memorize Pi is to break up a certain amount of digits into groups of 3 or 4. This allows you to take a little at a time, but it still gets done. Here is a great website for doing just that!
2. Use a song!
The way I memorized Pi at first was I listened to a song off of Youtube about 10,000 times. The digits all eventually got stuck in my head and I instantly knew 197 digits of Pi. Here's the song:
Click here to go directly to Youtube.