Elapsed time: The amount of time that passes between two events.
- Identify the start and end times
- Calculate hours first, then minutes
- If minutes in start time > minutes in end time, borrow an hour
- Combine hours and minutes for total elapsed time
Start: 3:45 PM, End: 4:20 PM
Hours: 4 - 3 = 1 hour
Minutes: 20 - 45 = ? Since 20 < 45, we need to borrow
Convert 1 hour to 60 minutes: 1 hour - 1 hour = 0 hours
Add to minutes: 20 + 60 = 80 minutes
Now subtract: 80 - 45 = 35 minutes
Total time = 0 hours 35 minutes = 35 minutes
Sarah read for 35 minutes
• Elapsed time: End time - Start time
• Borrowing rule: When minutes in start > minutes in end, borrow 1 hour = 60 minutes
• Time conversion: 1 hour = 60 minutes
Time conversion: Changing time from one unit to another (hours to minutes, etc.).
| Unit | Conversion Factor | Value |
|---|---|---|
| Hours to Minutes | × 60 | 2 × 60 = 120 minutes |
| Additional Minutes | No conversion needed | 25 minutes |
2 hours = 2 × 60 = 120 minutes
120 minutes + 25 minutes = 145 minutes
The movie lasted 145 minutes
The movie lasted 145 minutes
• Time conversion: 1 hour = 60 minutes
• Multiplication: Hours × 60 = minutes
• Addition: Total minutes = converted hours + original minutes
Start time calculation: Finding the beginning time when given end time and duration.
90 minutes = 1 hour and 30 minutes (since 90 ÷ 60 = 1 remainder 30)
Start time = End time - Duration
Start time = 5:00 PM - 1 hour 30 minutes
5:00 PM - 1 hour = 4:00 PM
4:00 PM - 30 minutes = 3:30 PM
The game started at 3:30 PM
The game started at 3:30 PM
• Start time: End time - Duration
• Time conversion: Convert total minutes to hours and minutes
• Subtraction: Subtract hours first, then minutes
Elapsed time: The difference between two times
Time conversion: Changing time from one unit to another
Time word problems: Real-world problems involving time calculations
- Read carefully: Identify start time, end time, and what is being asked
- Plan: Decide whether to calculate hours first or convert to common units
- Execute: Perform calculations with attention to borrowing/adding
- Verify: Check if the answer makes sense in context
• Hours to minutes: multiply by 60
• Minutes to hours: divide by 60
• Days to hours: multiply by 24
• Hours to days: divide by 24
• Elapsed time: End time - Start time
Time addition: Adding multiple time durations together.
50 minutes + 40 minutes = 90 minutes
90 minutes = 1 hour and 30 minutes (since 90 ÷ 60 = 1 remainder 30)
Tom practiced for 90 minutes total (or 1 hour 30 minutes)
Tom practiced for 90 minutes total
• Time addition: Add minutes together
• Conversion: When minutes ≥ 60, convert to hours
• Regrouping: Add converted hours to total hours
Time subtraction: Finding the difference between two time durations.
Total trip - Traveled = Remaining time
3 hours 20 minutes - 2 hours 45 minutes = ?
Hours: 3 - 2 = 1 hour
Minutes: 20 - 45 = ? Since 20 < 45, we need to borrow
Convert 1 hour to 60 minutes: 1 hour - 1 hour = 0 hours
Add to minutes: 20 + 60 = 80 minutes
Now subtract: 80 - 45 = 35 minutes
Remaining time = 0 hours 35 minutes = 35 minutes
The rest of the trip was 35 minutes long
• Time subtraction: Total - Part = Remaining
• Borrowing rule: When minutes in minuend < subtrahend, borrow 1 hour = 60 minutes
• Regrouping: Add borrowed minutes to original minutes
Elapsed time: The difference between two specific times
Time conversion: Changing time measurements from one unit to another
Time word problems: Real-life scenarios requiring time calculations
- Problem identification: Determine what type of time calculation is needed
- Unit selection: Choose appropriate time units for calculation
- Execution: Perform calculations following time arithmetic rules
- Verification: Check answer against problem context
• 1 minute = 60 seconds
• 1 hour = 60 minutes
• 1 day = 24 hours
• 1 week = 7 days
• Elapsed time = End time - Start time