Q. A lock has a code of 5 numbers from 1 to 10 . If no numbers in the code are allowed to repeat, how many different codes could be made?Answer:
Determine first digit choices: Determine the number of choices for the first digit of the code.Since there are 10 numbers to choose from and no restrictions for the first digit, there are 10 possible choices for the first number in the code.
Determine second digit choices: Determine the number of choices for the second digit of the code.After choosing the first digit, there are 9 remaining numbers to choose from for the second digit, since no number can be repeated.
Determine third digit choices: Determine the number of choices for the third digit of the code.Similarly, after choosing the first two digits, there are 8 remaining numbers to choose from for the third digit.
Determine fourth digit choices: Determine the number of choices for the fourth digit of the code.After the first three digits have been chosen, there are 7 remaining numbers to choose from for the fourth digit.
Determine fifth digit choices: Determine the number of choices for the fifth and final digit of the code.After choosing the first four digits, there are 6 remaining numbers to choose from for the fifth digit.
Calculate total number of codes: Calculate the total number of different codes that can be made.To find the total number of different codes, multiply the number of choices for each digit together.Total number of codes = 10×9×8×7×6
Perform final multiplication: Perform the multiplication to find the final answer.Total number of codes = 10×9×8×7×6=30240