If the only operation you are working with is addition you don't need to. However, if dealing with a long list of numbers, it may be useful to regroup into tens and hundreds and other "round numbers" that you can sum together quickly at the end.
For example 12 + 26 + 88 + 74
= 12 + 88 + 26 + 74 = (12 + 88) + (26 + 74) = 100 + 100 = 200
No
If the total in any column exceeds nine, you will have to regroup.
Yes.
Yes.
Regroup was created in 2006.
because 1 is toobig
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.
because sometimes the total is too big
yes because i said so losers
No
When the sum of the digits you are adding is 10 or larger.
38
If the total in any column exceeds nine, you will have to regroup.
no
The commutative property of addition and the commutative property of multiplication.
Yes.
No.