Adding and Subtracting Time

First add the seconds 45 + 25 = 70 seconds

Convert 70 seconds into minutes and seconds

70 seconds = 60 seconds + 10 seconds

Carry 1 minute to minutes column and write 10 in seconds column

Ans: 17 months 16 days and 10 hours

Step I: Add the hours

21 + 13 = 34 hours

             = 24 hours + 10 hours

             = 1 day 10 hours

Step II: Write 10 under hours and carry 1 to days.

Step III: Add the days.

1 + 25 + 20 = 46 days

                    = 30 days + 16 days

                    = 1 month 16 days

Step IV: Write 16 under days and carry 1 to months.

Step V: Add the months

1 + 9 +7 = 17 months

Write 17 under months

First add days, 4 + 5 = 9 days

Convert 9 days into weeks and days

9 days = 7 days + 2 days

           = 1 week and 2 days

Carry 1 to week column and write 2 in days column.

First subtract seconds

Since we cannot subtract 29 from 15, we borrow 1 minute. So, 15 + 60 = 75 seconds

75 – 29 = 46 seconds

Write 46 in seconds column

Now subtract minutes 23 – 18 = 5 minutes, write 5 in minutes column

First subtract the months

We borrow 1 year and subtract, 16 – 6 = 9 months

Write 9 in months column and now subtract 7 – 7 = 0

Write 0 in years column.

Step I: Subtract the minutes.

55 – 40 = 15 minutes

Step II: Subtract hours.

8 – 6 = 2 hours

Ans: 2 hours 15 minutes

Ans: 1 hour 55 minutes

Step I: We cannot subtract 50 minutes from 45 minutes.

So borrow 1 hour from 12 hours.

1 hour = 60 minutes

60 + 45 = 105 minutes

Step II: Subtract minutes.

105 – 50 = 55 minutes

Write 55 under minutes.

Step III: 12 – 1 = 11 hours remain in hours

Step IV: Subtract hours.

11 – 10 = 1 hour

Step V: Write 1 under hours.