Santiago hopes to buy a 4 horse trailer for about 12,000. describe all the numbers that when rounded to the nearest hundred are 12,000

Here are some numbers you round to 12,000: 11,789 12,013 12,432 11,500 11,999 11,679 or, 12,306 and there is plenty more but those are examples let me tell you why:
11,789
If your number is 11,000 over 500 then it rounds to the next number but if it is under 500 it goes to the regular number 11,000
here is another example:

12,013 it is the same with 11,000 but you want it to round to 12,000 so if it is under 500 it goes to 12,000 if it is over 500 then it goes to 13,000

How many shares did he have to begin with?