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Building number confidence: Time

2. Modern measures of time

Time is measured in different units. Here are some common time measurements and how they relate to one another:

Seconds, minutes, hours and days
  • 60 seconds in a minute
  • 60 minutes in an hour
  • 15 minutes in quarter of an hour
  • 30 minutes in half an hour
  • 24 hours in a day
  • 7 days in a week

A round clock with the numerals 1 to 12, placed in front of a page from a Calendar showing the month of November.
Days, weeks, months and years
  • 30 or 31 days in a month, except for February which has 28 (or 29 in a leapyear)
  • 365 days in a year (366 in a leapyear)
  • 4 weeks and 2 or 3 days in most months (February has exactly 4 weeks, or 4 weeks and 1 day in a leapyear)
  • 52 weeks in a year
  • 12 months in a year
  • 100 years in a century

 

Converting between units of time

As with other types of measurement, like length or weight, time can usually be converted into larger or smaller units using simple operations. For example:

  • There are 60 seconds in a minute, so to find how many seconds there are in 3 minutes, multiply 3 by 60: 3 × 60 = 120 seconds.
  • There are 60 minutes in an hour, so to find how many minutes there are in 4 hours, multiply 4 by 60: 4 × 60 = 240 minutes.
  • There are 24 hours in a day, so to find how many hours there are in 3 days, multiply 3 x 24: 3 x 24 = 72 hours.
  • There are 7 days in a week, so to find how many days there are in 12 weeks, multiply 12 by 7: 12 x 7 = 84 days.

Bear in mind that some conversions might require a little more consideration. For example, the number of days in 3 months may vary depending on the number of days in the months selected.

 

Time check

How many minutes are there in 3 hours?

180 minutes
There are 60 minutes in an hour. 60 x 3 = 180 minutes.


How many seconds are there in half an hour?

1800 seconds
There are 60 minutes in an hour, so half an hour is 30 minutes (60 ÷ 2). There are 60 seconds in a minute, so 30 minutes x 60 = 1800 seconds.


How many hours are there in two days?

48 hours
There are 24 hours in a day. 24 x 2 = 48 hours.


How many minutes are there in an hour and a half?

90 minutes
An hour is 60 minutes, and half an hour (60 ÷ 2) is 30 minutes. 60 + 30 = 90.


How many days are there in 6 weeks?

42 days
There are 7 days in a week. 6 x 7 = 42.