1. A method comprising: receiving written input, the written input being representative of a mathematical expression; analyzing the written input to identify at least one operator and at least one operand; constructing, via a processor, an expression tree based at least in part on predefined symbol relationships, the at least one operator, and the at least one operand; wherein constructing the expression tree includes inserting, based at least in part on the predefined symbol relationships, a placeholder within the expression tree for a missing operator, a missing operand, or a missing parenthesis and wherein the placeholder separately identifies whether the placeholder is for a missing operator, a missing operand, or a missing parenthesis; analyzing the expression tree to identify an error based at least in part on one or more predefined rules; and providing for display of a feedback message corresponding to the error, wherein the feedback message may include a suggestion for correcting the error.