Does anyone know the formula to calculate a 200 day EMA in an Excel spreadsheet? I know the formula for an exponential moving average is: X = (K x (C - P)) + P X = Current EMA C = Current Price P = Previous period's EMA* K = Smoothing constant (*A SMA is used for first period's calculation) and the smoothing constant is 2/(N+1) with "N" being the number of days in the average. This formula works for all of my other EMA's (5,10,20,50...) but it does not work for the 200. That is that the EMA's price in Excel using this formula does not match the EMA's price displayed on my charting software or the EMA displayed in a Java chart on Prophet.net. Why is this calculation not working for the 200 day EMA? Any help?