Since the combination can contain number (0-9) and letter (A-Z), therefore the total characters to choose from is:
10 + 26 = 36
Since there are 8 characters, therefore the total number of combinations is:
Combination = 36^8 = 2.821 x 10^12
The probability that the two will have similar passwords will be:
Probability = (1/2.821 x 10^12) ^2
Probability = 1.26 x 10^-25
The probability is very low.
