Addition is the mathematical operation of combining two or more numbers to get a total or sum.

Subtraction is the mathematical operation of taking one number away from another to find the difference.

Regrouping in addition refers to the process of carrying over a value from one column to the next when the sum exceeds the base value (e.g., 10 in base 10).

Regrouping in subtraction involves borrowing from a higher place value when the top digit is smaller than the bottom digit in a column.

To add two-digit numbers without regrouping, simply add the digits in each place value column separately, ensuring the sum is less than 10.

To add two-digit numbers with regrouping, add the digits in the ones place first, carry over if the sum is 10 or more, then add the tens place.

To subtract two-digit numbers without regrouping, subtract the digits in each place value column directly, ensuring the top digit is larger than the bottom.

To subtract two-digit numbers with regrouping, borrow from the next higher place value when the top digit is smaller than the bottom digit.

The sum of 246 and 553 is 799.

The difference between 974 and 621 is 353.