/= (Divide EQUALS) (Transact-SQL)
Divides one number by another and sets a value to the result of the operation. For example, if a variable @x equals 34, then @x /= 2 takes the original value of @x, divides by 2 and sets @x to that new value (17).
Returns the data type of the argument with the higher precedence. For more information, see Data Type Precedence (Transact-SQL).