Give the number whose hundreds place is one-third of the greatest one-digit number, the tens place is twice the hundreds place divided by 2, and the three digits in the thousands period is the product of the digits in the units period.

To find the number described in the question, let's break it down step by step:

Step 1: Find the greatest one-digit number.
The greatest one-digit number is 9.

Step 2: Determine the hundreds place.
The hundreds place is one-third of the greatest one-digit number.
One-third of 9 is 9/3 = 3.

Step 3: Calculate the value of the tens place.
The tens place is twice the hundreds place divided by 2.
Twice the hundreds place (3) is 2 * 3 = 6.
Divide it by 2, and the value of the tens place is 6/2 = 3.

Step 4: Find the value of the units period.
The units period consists of the three digits in the thousands period.
The problem states that the three digits in the thousands period are the product of the digits in the units period, but we don't have any information about the units period.

Given the information provided in the question, we can only determine the values of the hundreds place (3) and the tens place (3).

Therefore, the number would be 33.