To regroup the thousand block into hundreds, you divide the number of thousands by 10.
1,205 is made up of 1 thousand (which can be regrouped into 10 hundreds) plus 2 hundreds and 5 ones.
Therefore, 1,205 can be regrouped into:
1 thousand = 10 hundreds
2 hundreds = 2 hundreds
5 ones = 0 hundreds
So, regrouping 1,205 gives you a total of 12 hundreds (10 from the thousand and 2 from the two hundreds).
So, the answer is: 12 hundreds.