11. A non-transitory computer-readable storage medium comprising a combination of hardware and a computer program product having executable computer-readable program code instructions stored therein, the computer-readable program code instructions configured to: receive written input, the written input being representative of a mathematical expression; analyze the written input to identify at least one operator and at least one operand; construct 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 relationship, 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; analyze the expression tree to identify an error based at least in part on one or more predefined rules; and provide for display of a feedback message corresponding to the error, wherein the feedback message may include a suggestion for correcting the error.
11. A non-transitory computer-readable storage medium comprising a combination of hardware and a computer program product having executable computer-readable program code instructions stored therein, the computer-readable program code instructions configured to: receive written input, the written input being representative of a mathematical expression; analyze the written input to identify at least one operator and at least one operand; construct 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 relationship, 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; analyze the expression tree to identify an error based at least in part on one or more predefined rules; and provide for display of a feedback message corresponding to the error, wherein the feedback message may include a suggestion for correcting the error. 14. The non-transitory computer-readable storage medium of claim 11 , wherein the computer-readable program code instructions configured to construct the expression tree include being configured to construct a representation of the mathematical expression for display, the representation of the mathematical expression being determined based on a recursive analysis of one or more node tokens and corresponding nodes blocks within the expression tree.