Synchronous CDMA exploits mathematical properties of orthogonality between vectors representing the data strings. For example, binary string "1011" is represented by the vector (1, 0, 1, 1). Vectors can be multiplied by taking their dot product, by summing the products of their respective components (for example, if u = ("a", "b") and v = ("c", "d"), then their dot product u·v = "ac" + "bd"). If the dot product is zero, the two vectors are said to be "orthogonal" to each other. Some properties of the dot product aid understanding of how W-CDMA works. If vectors a and b are orthogonal, then formula_10 and: