1. Select "Custom" mode.
2. Adjust the settings to set the number of given digits to 50, health to 99, and gold to 9999.
3. Begin a game on the standard Sudoku board.
4. Use the upgrade available for 5 coins to unveil the potential numbers, applying it to each cell.
5. Input the correct numbers and repeat this process 500 times.

Overall, this is the quickest way to get the achievement. You need about 30-40 seconds per level and you can also combine the whole thing with the other achievements and play on the different levels to get the 100 Nonomino Sudokus and 100 Overlapped Classics Sudokus achievements aswell.