Problem Set 45 – Adding and Subtracting TimeClass 5 Maths · Chapter 10 Measuring Time · Problem Set 45 – Maharashtra Board

Summary: Problem Set 45 – Adding and Subtracting Time

Write hours under hours and minutes under minutes, and work on the minutes first.

When adding, if the minutes come to 60 or more, change 60 minutes into 1 hour and carry it: 75 min = 1 h 15 min.

When subtracting, if the top minutes are too few, borrow 1 hour and turn it into 60 minutes.

Duration problems: use the 24-hour clock and subtract (11:00 to 15:30 = 4 h 30 min), or jump to 12 noon first and add the pieces.

An end time = start time + duration: a film at 4:20 pm lasting 2 h 50 min ends at 7:10 pm.

Key points to remember

• 1 hour = 60 minutes
• Hours under hours, minutes under minutes
• Do minutes first
• Adding: 60 minutes or more → carry 1 hour
• Subtracting: borrow 1 hour = 60 minutes
• Duration = end time − start time
• Use the 24-hour clock for afternoon times
• Overnight: count to midnight, then add

Problem Set 45 – Adding and Subtracting Time – Notes

1. Adding hours and minutes

• Add minutes, then hours.
• If the minutes are 60 or more, take away 60 and add 1 to the hours.
• 1 h 50 min + 2 h 25 min = 3 h 75 min = 4 h 15 min.

2. Subtracting hours and minutes

• 6 h 10 min − 3 h 45 min: 10 − 45 is not possible.
• Borrow 1 hour: 6 h 10 min = 5 h 70 min (60 + 10).
• 70 − 45 = 25 min; 5 − 3 = 2 h → 2 h 25 min.

3. How long is it open?

• A clinic opens at 8:30 am and closes at 5 pm.
• Method 1: 8:30 → 12 noon = 3 h 30 min; 12 noon → 5 pm = 5 h; total 8 h 30 min.
• Method 2: 24-hour clock: 17:00 − 08:30 → borrow: 16 h 60 min − 8 h 30 min = 8 h 30 min.

4. When does it end?

• Add the duration to the start time.
• A film starts at 4:20 pm and lasts 2 h 50 min: 20 + 50 = 70 min = 1 h 10 min; 4 + 2 + 1 = 7 → 7:10 pm.
• Two and a half hours = 2 h 30 min.

5. Journeys over midnight

• A train leaves at 16:45 and arrives the next day at 09:20.
• 16:45 → 24:00 (midnight) = 7 h 15 min. Midnight → 09:20 = 9 h 20 min.
• 7 h 15 min + 9 h 20 min = 16 h 35 min.

Formulas at a glance

Key terms

Problem Set 45 – Adding and Subtracting Time – Flashcards

Read the question, answer it in your head, then tap the card to check. 10 cards.

Problem Set 45 – Adding and Subtracting Time – MCQ Quiz

10 questions. Tap an option — you will see at once if it is right and why.

How to study Problem Set 45 – Adding and Subtracting Time

⏱ About 25 minutes

1. Learn (5 min)
   Learn to carry 60 minutes as 1 hour and to borrow 1 hour as 60 minutes.
2. Solve (15 min)
   Add and subtract times, then try opening-hours and journey problems.
3. Practise (5 min)
   Do the 4 'Try it yourself' sums, take the quiz and play 🎮 Play.