1. An electronic calculator comprising: keyboard input means including a plurality of operand and operator keys for entering a line of at least one algebraic statement into the calculator, one of said plurality of keys being operative for entering a minus arithmetic operator into the calculator; memory means for storing a line of at least one algebraic statement entered into the calculator from said keyboard input means; processing means, coupled to said keyboard input means and memory means, for processing a line of at least one algebraic statement entered into the calculator and stored in said memory means to perform the algebraic operations specified in that line of at least one algebraic statement; and output means, coupled to said processing means, for providing a visual indication of the results of algebraic statements processed by said processing means; said processing means being responsive to the combination of the minus arithmetic operator followed by an operand, encountered during processing of an algebraic statement, for negating that operand, said processing means being further responsive to the combination of a first operand followed by the minus arithmetic operator followed by a second operand, encountered during processing of an algebraic statement, for subtracting the second operand from the first operand.