Multi-Digit Addition and Subtraction Flashcards

Question 1

What is regrouping (carrying) in addition?

Accepted Answer

Regrouping is trading $10$ of one place for $1$ of the next place: if a column sum is $\ge 10$, write the ones digit and add $1$ to the next column.

Question 2

What is the difference between regrouping in addition and borrowing in subtraction?

Accepted Answer

In addition, you regroup when a column sum is $\ge 10$ and carry $1$ to the next place. In subtraction, you regroup when the top digit is smaller and you take $1$ from the next place to add $10$ to the current place.

Question 3

When do you use estimation for sums and differences in multi-digit operations?

Accepted Answer

Use estimation to check if an exact answer is reasonable, to plan mental math, or when an approximate value is enough (e.g., quick comparisons or budgeting).

Multi-Digit Addition and Subtraction Flashcards

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