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### Course: Get ready for 6th grade>Unit 1

Lesson 2: Convert units of measure

# Converting units of time

Learn to convert hours, minutes, and seconds. Created by Sal Khan.

## Want to join the conversation?

• how many second are there in a year
• 31,536,000 seconds
• what if it was 5 seconds ? How do you convert that into minutes?
• I think that would be 1/12 of a minute as 5 seconds is 5/60 of a minute. 5/60 simplified is 1/12.
• how many seconds are there in a century?
• There are 31,536,000 seconds in a century. This is because there are 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day, and 365.2425 days in a year on average (leap years are taken into account), and 100 years in a century. Thus, there are 60 * 60 * 24 * 365.2425 * 100 = 31,536,000 seconds in a century.
• it still doesn't make sense.. could you be more specific?
• So the video is trying to show you how to figure out how many seconds are in a given number of minutes or how many minutes are in a given number of hours. Instead of actually counting this out, you can just remember that one minute has sixty seconds in it and that one hour has sixty minutes in it, so if you have 7 minutes and you're trying to figure out how many seconds are in that. All you really need to do is multiply 7 by 60. Similarly, to find how many minutes are in a given number of hours, you do the same thing. If you're trying to find the number of seconds in a certain amount of hours, you would multiply by 3600. (the number of seconds in an hour)
• At , Sal says that 1 minute = 60 seconds by definition. Similarly, at , Sal says, "We know by definition 1 hour = 60 minutes."
How were a second, minute, and hour defined? Why is 1 minute 60 seconds and 1 hour 60 minutes? What rationales do these facts rest on?
• At , Sal says that 1 minute = 60 seconds by definition. Similarly, at , Sal says, "We know by definition 1 hour = 60 minutes."
How were a second, minute, and hour defined? Why is 1 minute 60 seconds and 1 hour 60 minutes? What rationales do these facts rest on?
(1 vote)
• What is the amount of time with two minutes / 3
• Really sorry for late reply, but that is 2/3 of a minute, or 40 seconds.
• How many seconds are in a decade
(1 vote)
• Decade represents value of 10 years.

We know that one year has + - 365 days (to make the calculations simple. So 10 * 365 days.
One day has 24 hours. Which means we got (days: 10 * 365) * 24 hours!
one hour has 60 minutes. so we got (days: 10 * 365) * (hours: 24) * (minutes: 60)
And one minute has 60 seconds.
So the whole looks like this:
(days: 10 * 365) * (hours: 24) * (minutes: 60) * (seconds: 60)
which is
10 * 365 * 24 * 60 * 60
which is
3650 * 24 * 3600
which is
315,360,000.

So there are 315,360,000 (315 millions, 360 thousand) seconds in a decate.
(1 vote)
• So what ever hour you get, you just times it with 60. Once you get the answer for that you times it buy 3600? And you get the total answer?
(1 vote)
• How many hours in 3 years
(1 vote)
• It would depend on if any of the years are leap years.

24 hours per day X 365 day per year x 3 years = 26,281

If one of the years is a leap year, it would have one more day, or 24 more hours -- 26,304
(1 vote)
• When did people think of the word time?
(1 vote)
• I Actually have no Idea. An idea though is to try and check history. I'm betting it would give you information.
(1 vote)

## Video transcript

We have multiple lengths of time here, and they're measured in minutes. So what we want to do is say, well, what's an equivalent number of seconds? And so the first one is pretty straightforward. 1 minute is equal to 60 seconds. By definition, a second is 1/60 of a minute. But what about 5 minutes? Well, we could try to visualize that. If 1 minute-- so let's say that is 1 minute-- if that is equal to 60 seconds, then 5 minutes-- let's just make five copies of this. So that's 1, 2, minutes, 3, minutes, 4 minutes, and then 5 minutes. So you see that 5 minutes would be 5 times 60 seconds. And 5 times 60 is 300. So here you have so this is going to be 5 times 60, which is equal to 300 seconds. So what about 10 minutes? Well, same idea. 10 times 60 is 600 seconds. And what about 60 minutes? Well, 60 minutes or 60 seconds per minute times 60 minutes is equal to 3,600 seconds. So that's interesting. Let's take things a little bit further other. Let's convert between hours, minutes, and seconds. So let's start off with something that's a little bit more straightforward. Let's say that we have 1 hour. Well, we know by definition 1 hour is equal to 60 minutes. And how many seconds is 60 minutes equal to? Well, we just figured that out. 60 minutes times 60 seconds per minute gets us to 3,600 seconds. Now, what about 2 hours? Well, it would be the same exact idea. 60 minutes per hour, if I have 2 hours, it's going to be 2 times 60. 2 hours times 60 minutes per hour gets us to 120. Well, how many seconds is that going to be? Well, there's a couple of ways you could think about it. You could take 120 minutes times 60 seconds per minute. Or you could say 2 hours times 3,600 seconds per hour. So let's do it that way. So two 2 times 3,600 seconds per hour gets us to 7,200 seconds. Now, what if we were to say 10 hours? Well, once again, 10 times 60, 10 hours times 60 minutes per hour would get us to 600 minutes. And if we want to think in terms of seconds, 10 hours times 3,600 seconds per hour gets us to-- well, it's going to be 3,600 tens, which would be 36,000, or 10 times 36 hundred, or 10 times 3,600.