Questions on basic arithmetic involving numerical quantities only. Questions involving variable values (other than the result of the operation) should be placed under the (algebra-precalculus) tag. Questions about number theory (sometimes called "arithmetic") should not use this tag and should instead use (number-theory) or (elementary-number-theory).
Arithmetic is defined as operations upon numbers using $4$ main operations along with many others:
addition - the sum of two numbers
subtraction - the difference of two numbers also defined as the addition of negative numbers
multiplication - the area of a rectangle with sides of lengths equal to the two operands
division - the number of times one number can be subtracted from another before equaling zero. Sometimes it will allow decimals and in other cases there will be a remainder left over when a number doesn't go into another evenly