Prior to October 2015, players of the UK National Lottery chose 6 different numbers from 1 to 49. In the lottery draw, 6 numbered balls are selected at random without replacement. If the player correctly guesses all 6 numbers (in any order), they win the jackpot. a. What was the probability of winning the jackpot in the UK National Lottery prior to October 2015?
b. After October 2015, the game was slightly changed. Now, players choose 6 different numbers from 1 to 59. How did this change alter the probability of winning the jackpot?

The method i was trying to use was for a , 49*48*47*46*45*44 and take a reciporal of that , the same applies to b,

however, the answer is wrong as the correct one uses combination, i dont understand why i cant use permutation in this question, thanks