Page 161 - Mathematics_Std_4

10. hours minutes 11. hours minutes 12. hours minutes
3 55 8 15 4 35
− 1 45 − 5 05 − 1 20

FOR ONLINE READING ONLY

13. hours minutes 14. hours minutes 15. hours minutes
7 30 6 48 2 45

− 2 15 − 3 40 − 1 05

Subtraction of measurements of time with regrouping
Measurements of time can be subtracted with regrouping. This

should be done by considering the relationship existing between
the units of time.

Example 1

hours minutes
3 15

− 1 45

Steps Solution
1. Subtract minutes: 15 – 45, it is not hours minutes
sufficient. Take 1 hour from the 3 hours, 2 75
then convert it into 60 minutes. Add − 1 45
=
minutes:60 15 75. Now, subtract
+
=
−
minutes: 75 45 30. Write 30 in the 1 30
minutes column. Remember that, two
2 hours remained in the hours column.
2. Subtract hours: − =2 1 1.Write 1 in the
hours column.

Therefore, the answer is 1 hour 30 minutes.

154

07/11/2024 14:06:42
MATHEMATICS STD 4 PB 2024.indd 154
MATHEMATICS STD 4 PB 2024.indd 154 07/11/2024 14:06:42