Page 147 - Start Up Mathematics_4

Given below are the steps for subtracting time.

1. If the number of minutes being subtracted is more than the original minutes, then:
(a) borrow 1 hour or 60 minutes from the original hours.

(b) subtract 1 from the original number of hours.
(c) increase the number of original minutes by 60.

2. Subtract the minutes.
3. Subtract the remaining hours.

Example 8: Subtract 3 h 35 min from 8 h 50 min.

Solution: h min A Challenge!
4 10
8 5 0 Add 5 h 40 min, 6 h 35 min,
and 55 min. From their sum,
– 3 3 5
subtract 8 h 50 min.
5 1 5

So, 8 h 50 min – 3 h 35 min = 5 h 15 min.

Example 9: Subtract 9 h 55 min from 13 h 30 min.

Solution: h min
12 9 0 (30 + 60 = 90)
1 3 3 0 (1 h = 60 min)
– 9 5 5

3 3 5

So, 13 h 30 min – 9 h 55 min = 3 h 35 min.

EXERCISE 10.5

1. Add.

(a) 2 h 20 min and 8 h 40 min (b) 3 h 15 min and 5 h 30 min
(c) 7 h 40 min and 10 h 25 min (d) 12 h 45 min and 15 h 35 min
(e) 16 h and 14 h 50 min (f) 19 h 25 min and 13 h 50 min

2. Subtract.

(a) 4 h 20 min from 7 h 45 min (b) 6 h 25 min from 10 h 10 min
(c) 11 h from 15 h 30 min (d) 12 h 35 min from 18 h 50 min
(e) 9 h 50 min from 14 h 45 min (f) 13 h 55 min from 21 h 40 min

Duration of Time

Duration of time means the time between the happening of two events or the time passed.

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