Manual Arithmetic
A typical example of carry is in the following pencil-and-paper addition:
¹ 27 + 59 ---- 867 + 9 = 16, and the digit 1 is the carry.
The opposite is a borrow, as in
−1 47 − 19 ---- 28Here, 7 − 9 = −2, so try (10 − 9) + 7 = 8, and the 10 is got by taking ("borrowing") 1 from the next digit to the left. There are two ways in which this is commonly taught:
- The ten is moved from the next digit left, leaving in this example 3 − 1 in the tens column. According to this method, the term "borrow" is a misnomer, since the ten is never paid back.
- The ten is copied from the next digit left, and then 'paid back' by adding it to the subtrahend in the column from which it was 'borrowed', giving in this example 4 − (1 + 1) in the tens column.
Read more about this topic: Carry (arithmetic)
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