relative vs. absolute references

A1 -- relative reference
$A$1 -- absolute reference

A1 style
r1C1 style

what happens when your formula is wrong?
how do you find the "bug" and fix it?
Grace Hopper
http://en.wikipedia.org/wiki/Grace_Hopper

Sum function
range operator
:
cell ref : cell ref

hw: midlevel and capstone exercises, ch 2, excel