Press to access the numerical integration option (nInt), which approximates the definite integral of an expression with respect to a variable from a start value to an end value.
The syntax is: nInt( expression, variable, start value, end value )
For example, to find the integral of x3 evaluated from x = 1 to x = 2 numerically, enter
Note: The accuracy goal of the calculator's algorithm is 6 significant digits. A warning ("Questionable accuracy") is displayed when it appears that the goal has not been obtained. For more specific information and tips see Integration on the TI-how does it work?