2. In basic arithmetic, carry is a form of operation. In addition, when the number on each digit is equal to the radix, it is part of the standard algorithm to move forward by one digit. Merge from the rightmost number and pass it to the left.

3. When carry is used for subtraction, this operation is also called borrow.

4. In advanced mathematics, Kummer's theorem points out that P plus two digits is equivalent to the exponent of the greatest power of P divided by a binomial coefficient.

5. When several random numbers of multiple numbers are added, the statistical data of decimal places are related to Euler numbers and the statistical values of mixed random arrangement.

6. The carry operation of two digits can be formalized in abstract algebra with group homology language, and this view can be applied to the alternative representation of real numbers.