Question

How many different 2-digit ID numbers can be made if each ID number can use the numbers 1 through 8 and no digits may be repeated?

Answer 1

Answer:1,2,5,7,8 and 9. Thus, we have 6 numbers.

Step-by-step explanation:Then we want to form two-digit numbers without repetition. There are 6 number that is possible to occupy first digit, right? 1,2,5,7,8 or 9. Because it’s without repetition, so the number that have been filled the first digit cannot be the second digit. Thus, the numbers that possible to occupy second place are 5 digits.So step by step