In the Software-as-a-Service (SaaS) parlance 'Magic Number' is basically a metric that measures the sales and marketing efficiency of a SaaS firm. It captures how many dollars' worth of revenue is generated per dollar spent on acquiring new customers through sales and marketing. The metric helps organisations optimise their marketing expenses and reduce overall customer acquisition costs. It is much talked about now more than ever as the SaaS firms are bracing for tight macroeconomic conditions. A Magic Number below 0.5 means that the firm cannot invest more in Sales and Marketing. Magic Number above 0.75 is ideal for small and big businesses.