If you have to have at least one group of each, there are four.
25
8 tens.
4/-3 8
With addition, you need to regroup in the event that there are more than 10 ones or 10 tens. In a subtraction, you must regroup whenever there are insufficient ones or tens to subtract.
1 tens and 2 0nes
500+10+6 = 516
(3*10)+(9*1)=39
78 can be regrouped into 6 tens and 18 ones.
8 tens and 4 one
To take the tens place and add it to the other tens
How would you regroup 4 tens to find the difference between 341 and 228?
8 tens 2 ones