There are a few frustrating things you'll run into as you learn Excel or anything for that matter. Learning new things is difficult. By making this book little, hopefully you'll be less overwhelmed.
Excel can display an error and you won't know why. This is usually where people either love or hate Excel. The lovers will figure out what's causing this problem and the haters will quit very quickly.
Losing Your Keys
Have you ever lost your keys or wallet? I have and it's the same process, look all over the house, look again in the same areas (as if the keys will magically appear there) and then by accident you find it on the window sill, just where you put it.
When you solve a problem it's always so obvious that you should have looked there immediately. Excel problems are the same. Once you've found out the solution it's always obvious.