What is carry the zero?

"Carry the zero" is a term commonly used in mathematical operations where a number that is too large to be accommodated in a single digit place value of a mathematical operation is carried over to the next digit place value. This occurs mostly in addition and subtraction, where the number in a particular digit place value exceeds 9 (in base 10) or overflows the maximum permissible value.

For instance, in the addition of 725 and 396, the digit values need to be stacked vertically, from right to left. Starting from the last-digit pairing, 5 + 6 results in 11, which is too large for a single digit. The one in the 11 is written down, and the other one in the usual "10's place." That addition of the 1 to the next, higher-order place is referred to as "carrying" the one or "carrying the zero".

In short, this technique allows for the handling of larger numbers beyond the capacity of a single digit.