Roughly 23 minutes.
Ahh, isn't that just super fun to say? "Summation Notation" is displayed with the capitol Greek letter Sigma ( Σ ). Anyway, let us get started.
Create a new program and name it "SUMMNOTA" (Or whatever will help you remember what it is)
Press "prgm", go to the "I/O" tab, and select "Input"
Type ""EXPRESSION (USING X): "", then press comma (Omit "(USING X)" if on TI-83)
Press "vars", go to "String" and select "Str1". Start a new line
Repeat step 2 and type ""START ",Y". Start a new line
Repeat step 2 and type ""END ",Z". Start a new line
Get "Str1" again and press "sto→"
Press "vars", go to the "Y-VARS" tab, go to "Function", and select "Y₁". Start a new line
FOR TI-84 (Skip to FOR TI-83 if you have a TI-83):
Press "math" and select "summation Σ("
Get "Y₁" again and type ",X,Y,Z)→S". Start a new line
FOR TI-83:
Press "2nd" "stat", go to the "MATH" tab, and select "sum("
Press "2nd" "stat", go to the "OPS" tab, and select "seq("
Get "Y₁" again and type ",X,Y,Z,1))→S". Start a new line
FOR BOTH:
Press "prgm", go to the "I/O" tab, select "Disp", and type "S"
The programs should look accordingly:
TI-84
:Input "EXPRESSION (USING X): ",Str1
:Input "START: ",Y
:Input "END: ",Z
:Str1→Y₁
:Σ(Y₁,X,Y,Z)→S
:Disp S
TI-83
:Input "EXPRESSION: ",Str1
:Input "START: ",Y
:Input "END: ",Z
:Str1→Y₁
:sum(seq(Y₁,X,Y,Z,1))→S
:Disp S
Explanation time! Firstly, the reason we have to store our expression as a string first is because we cannot store an input directly to Y₁, and the reason we have to store the string as Y₁, is because summation and sequence will not use strings as input data. This was the happy medium. Secondly, summation on the TI-83 is NOT a thing, so we have to add up a list of numbers, following the rule we put in. What those variables mean is seq(rule,variable,first,last,increment), and sum will add all the numbers that are output. Lastly, what the variables in summation are: Σ(rule,variable,bottom,top). Summation notation, or sigma notation, is denoted with the rule to the right, the starting variable on bottom, and the final variable on top, which is what we input with this program. Basically, this program will make your math life easier, and if you decide to play with it a little more to understand it fully, you can even write your own programs for other math classes.
Give this a like if it was helpful. Drop a comment if you have a question or need help. Thanks for reading!
-Nate