A processor on a delegator receives an input upon which an expensive function is to be evaluated. The delegator incorporates the input into a request to perform a task that is different from evaluating the function. When the task is performed, it provides a secondary result that is observable by the delegator. The secondary result is different from an answer to the expensive function and can be verified by the delegator with less computational expense than evaluation of the expensive function. The task can be performed by the server only after the server has verifiably evaluated the function based on the input. Request data, that is indicative of the request to perform a task with the input incorporated therein is transmitted to the server for performance of the task. The delegator then receives a returned result from the server indicative of the server performing the task. The returned result has a value that reflects both an answer to which the server has evaluated the function, and whether the answer is verified as being correct.