histogram bins and bin widths
When making a histogram, you can either specify Bin Width or Number of Bins, but not both. You should be able to do both!!! Especially if you have to create multiple histograms to compare to one another. If the data is slightly different, excel is going to format them both differently and then you are unable to properly compare them.
Also, if you try to create a histogram using the Data Analysis Tool Pack, it spaces out the bars making this a bar graph, NOT a histogram.