Sum of a sequence?

So, I needed to find the sum of all the numbers between 1 and 230, so I did it by hand on my calculator, which took forever. Now I have to find the sum of all the multiples of 5 from 1 to 100 ((5*1)+(5*2)+(5*3)+(5*4)...etc.). I have a TI-83 calculator, and I imagine there is a cool way of doing this on there, rather than doing it by hand (i.e. for the first problem 1+2+3+4+5.... etc.). Does anybody know if there is a function on my calculator that will do this for me? And if so, what is it called? I have the manual for the calculator, so I can look up the syntax, etc.