To regroup, you simply break up the bigger numbers into smaller numbers that are more easily added together. We often regroup numbers into numbers that end with 0 because they're easier to add. For example, you can break up 64into 60+4 and 43 into 40+3. This will make addition easier, because you can first add together 60 and 40, which is equal to 100. Then, you can add the smaller digits 100+4+3=107.
