The Number Pi (π) - 500,000 Decimals: Ideal present or gimmick for

One Million Digits of Pi On One Page!- [Plus Guides And Information]

Michael Shermer, Arthur Benjamin - Secrets of Mental Math--The Mathemagician's Guide to Lightning Calculation and

The Magic Cafe Forums - PI REVELATIONS by David Penn (A mind blowing system! - Peter Turner)

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5 Million Digits of Pi - Volume 5 - Decimal Places from 20,000,001 to 25,000,000: 5th 5000000 decimal places; 8000 digits on page; Digit counter on

Getting to Know Pi!