Bunuel wrote:

How many odd 4-digit positive integers that are multiples of 5 can be formed without using the digit 3?

A. 648

B. 729

C. 900

D. 1296

E. 3240

We need to determine the number of odd 4-digit positive integers that are multiples of 5 and can be formed without using the digit 3. Thus, we know that the last digit is 5.

So, we have 8 options for the first digit (because the first digit can’t be 0 or 3), 9 for the second (can’t be 3), 9 for the third (can’t be 3), and one for the fourth (must be 5). Thus, we have 8 x 9 x 9 x 1 = 648 options.

Answer: A

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