Another way is the following:
wind angle + 20 = %
Eg:
runway 27 = runway heading 270°
W/V 300°/20 kts
wind angle = 300 - 270 = 30
30 + 20 = 50% of the wind speed (20 kts), so the crosswind component is 10 kts.
A wind angle of 80° or more means that the full wind speed is the crosswind component, and wind angles of 0 - 10° = no crosswind.
I hope this helps.