To solve this problem, let's break it down step by step.

1. Final Rounding to the Nearest Thousand:

   • The number rounds to 7000 when rounded to the nearest thousand. This means the original number must be in the range from 6500 to 7499.

2. Before the Final Rounding (Nearest Hundred):

   • We need to determine what the number could have been before it was rounded to the nearest hundred.
   • If the number rounds to 7000 when rounded to the nearest thousand, it must have been in the range 6950 to 7049 after rounding to the nearest hundred.

3. Before the Rounding to the Nearest Hundred (Nearest Ten):

   • The number was initially rounded to the nearest ten, and then that result was rounded to the nearest hundred.
   • To round to a number within 6950 to 7049 when rounding to the nearest hundred, it must have been in the range 6945 to 7054 when rounded to the nearest ten.

4. Finding the Least Possible Original Number:

   • To find the smallest possible original number, we consider the lower boundary of each step.
   • If we start from the smallest possible result after rounding to the nearest ten, which is 6945, we check the smallest number that would round to 6945:
     • A number like 6944.5 would round to 6945, but it must be an integer, so we consider 6945 itself.
   • Now, to get 6945 when rounding to the nearest ten, the smallest possible number is 6940.

Thus, the least possible number it could be is 6940.

---

Would you like more details, or do you have any questions? Here are some related questions:

1. How does rounding affect significant figures in a number?
2. What are the rules for rounding to the nearest ten, hundred, and thousand?
3. How does rounding influence data accuracy in measurements?
4. Can you demonstrate rounding for a number with decimals before applying it to larger scales?
5. How would this problem change if the number rounds to 8000 instead of 7000?

Tip: When solving rounding problems, always consider the range that a number falls into before and after rounding to better understand the possible original values.