the answer is quite simplelet the 3 digit code be made up of 3 digitsfor every digit, we can let it be ,1,2,3,4,5,6,7,8,9 a total Of 10 optionsfor the next digit, we can have a total of 10 options as well, same for the 3rd digit.therefore the no. Of combinations would be 10 choices for the first digit * 10 choices for the 2nd digit * 10 choices for the 3rd digit = 10*10*10 = 1000