[QUOTE=bose-x;9840772]Blimey. Just look at the windsock. You really don't need to know numbers.[/QUOTE
It is a good idea to use a simple system 30/45/60 degrees from the early days so that when you need to assess the crosswind in IMC it is second nature. It's is actually very easy.
Look at your watch 30 degrees = 30 minutes= half an hour...half the wind is cross wind.
45 degrees is 3/4 of an hour = 3/4 of the wind is cross wind
60 degrees is a full hour...all crosswind.