It takes 10 minutes and 57 seconds to type five times, and 10 seconds to type eight words all the time. 10 minute 57 seconds equals 657 seconds, five times eight seconds equals 40 seconds, 657 ÷ 40 = 16.425. Knock every 16.425 seconds. The clock strikes 8 times every 80 seconds, once every 80 ÷ 8 = 10 second.