Given the number of dice and the sum we want to get the chance of, return the chance rounded to 2 decimals, formatted as shown (with the % at the end).
chance(3, 6) ➞ "4.63%"
# There is approximately 4.63% chance for rolling 6 with 3 dice.
chance(5, 20) ➞ "8.37%"
chance(2, 7) ➞ "16.67%"N/A