How many 3-digit odd numbers can be formed with the digits 1, 2, 3, . . . , 9, if no digit is repeated in any
pls help on the problem above, thanks.
Can you think of a sequence of steps to construct such a number? E.g., "at first I choose the last digit, then ..." Try to calculate in how many ways each step can be done. Then usually you have to multiply the numbers for each step. It is important that all possible numbers can be constructed using these steps, and no number is constructed twice using different choices.