Few months back I wrote a post on rounding numbers to no decimal place with a macro. It is particularly useful when you have too many numbers in a spreadsheet like financial model. Please pardon my ignorance, Excel has a mouse based shortcut to do this.
Home -> Style -> Cell styles -> Number format -> Comma
648523.2363 -> Comma -> 648,523
I m just came to know about it a little late
Pressing Ctrl, Alt and/or Shift keys in combination with other keys can render you some really useful shortcuts. One more is here.
If you want to make same changes in two or more worksheets of a workbook, press CTRL and with mouse select the other worksheets. You will notice a slight tab color change in selected sheets.
In picture above I colored tab dark blue to see the change easily. Any operation you are doing in first work sheet, will be replicated in the other selected sheets in same cells. Be it text or formula entry, insert row column, color or just any other thing. Enjoy !