WEBVTT 00:00:00.004 --> 00:00:03.718 So let's try an example. Suppose we wanted to find the days between dates. 2013 00:00:03.718 --> 00:00:08.686 Janurary 24, and 2013 June 29th. If we were going to do this as a human we might 00:00:08.686 --> 00:00:13.366 look at a calendar. I happen to have a calendar handy and thanks to my auntie in 00:00:13.366 --> 00:00:17.086 Belfast for sending me the calendar and we could count the days using the 00:00:17.086 --> 00:00:22.463 calendar so let's look at the calendar. We have our starting day is January 24 00:00:22.463 --> 00:00:27.581 and we might count the days between January 24. How many do we have left in 00:00:27.581 --> 00:00:32.701 January. So there would be 1,2, 3, 4, 5, 6, 7 days left in January. So there'd 00:00:32.701 --> 00:00:37.890 be seven days in January. Then we have, have all of February, all of February is 00:00:37.890 --> 00:00:46.209 28 days. Then we have all of March, 31 days. All of April, 30 days. All of May, 00:00:46.209 --> 00:00:52.367 31 days. And then we have June. We don't want to count all of June because we 00:00:52.367 --> 00:00:58.132 are stopping on June 29th, so we are going to add 29 days. From June, and if we 00:00:58.132 --> 00:01:03.206 sum all those up we should get our answer. And as a human we know how to compute 00:01:03.206 --> 00:01:07.072 sums by entering sums into Google, and we get 156.