Converting Time and Calculating Time

The basic units of time are seconds, minutes, hours, and days.

We use these units to measure how long something takes. Here are some important conversions to remember:

• 1 day = 24 hours

• 1 hour = 60 minutes

• 1 minute = 60 seconds

Knowing these helps you easily switch between different units of time.

When converting units of time:

• Multiply when changing to a smaller unit (hours → minutes → seconds).

• Divide when changing to a larger unit (seconds → minutes → hours).

✏️ Example 1: Convert 2 hours to minutes

We know 1 hour = 60 minutes.

To find out how many minutes are in 2 hours, multiply by 60:

$$ 2 \times 60 = 120 \text{ minutes}$$

✏️ Example 2: Convert 300 seconds to minutes

We know 60 seconds = 1 minute.

To find out how many minutes are in 300 seconds, divide by 60:

$$ 300 \div 60 = 5 \text{ minutes} $$

Example: Add 35 minutes 20 seconds and 20 minutes 45 seconds.

• Step 1: Add the minutes and the seconds separately.
  Minutes: 35 + 20 = 55 minutes
  Seconds: 20 + 45 = 65 seconds

• Step 2: Convert seconds if needed.
  Since 65 seconds exceeds 60 seconds, we convert it into 1 minute and 5 seconds.

• Step 3: Add everything together.
  Add the extra 1 minute to 55 minutes to get 56 minutes.
  Combined with the 5 seconds.
  The final answer is 56 minutes and 5 seconds.

Example: Subtract 54 minutes 23 seconds from 56 minutes 5 seconds.

• Step 1: Set up the problem.
  You want to do: 56 min 5s – 54 min 23s

• Step 2: Borrow 1 minute.
  Since 5 seconds is too small to subtract 23 seconds, you need to borrow 1 minute from 56 minutes.
  Since 1 minute equals 60 seconds, now you have: 55 min 65s – 54 min 23s

• Step 3: Subtract minutes and seconds separately.
  First, subtract minutes: 55 min – 54 min = 1 min
  Then, subtract seconds: 65s – 23s = 42s
  So, the final answer is: 1 min 42s