Write the greatest odd number that uses the digits 3 4 5 once each

I vote for 43^5 which is greater than 147 million. = 147008443

and it is odd.

543

I vote for 3^4^5 ≈ 10^488

543

To find the greatest odd number that uses the digits 3, 4, and 5 once each, we need to consider the positioning of these digits.

Let's start by analyzing the last digit. To form an odd number, the last digit must be either 3 or 5. Since we want the greatest possible number, let's choose 5 as the last digit.

Moving to the tens digit, we have only 3 and 4 left. Again, we want the greatest possible number, so we use 4 as the tens digit.

Finally, for the hundreds digit, we have only 3 left.

Putting it all together, the greatest odd number using the digits 3, 4, and 5 once each is 453.

Therefore, the answer is 453.