Crosswind - the simple (on final) mental calculation
Split the watch face into 4 quarters - 1 to 3 = 1/4, 3 to 6 = 1/2, over 6 = full crosswind
Wind 10-30 deg off runway is in the first 1/4 - take 1/4 of wind as crosswind
Wind 30-60 deg off runway is in the second quarter - take 1/2 of wind as crosswind
Wind 60 deg + take all of wind as crosswind