a lost interview with co-inventor j. presper eckert. (via digging-deeper-than-telling robert. muchas gracias guapo;)

Well, a person with a paper and pencil can add two 10-digit numbers in about 10 seconds. With a hand calculator the time is down to 4 seconds. The Harvard Mark 1 was the last of the electromechanical computers -- it could add two 10-digit numbers in 0.3 seconds, about 30 times faster than paper and pencil.