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    E:\Working\Orange_Education\TouchPad_Maths_4\Open_Files\Chap_11\Chap_11
                     \ 10-Nov-2025  Bharat Arora   Proof-8                                    Reader’s Sign _______________________ Date __________

                    AddiTion And SubTRACTion oF Time

                    example 1. Add 28 minutes 32 seconds and 24 minutes 42 seconds.

                    Solution. Write the times in columns correctly and then add.
                    Step 1.  Add the seconds.                                                                   min     s
                                                                                                                  1
                              32 s + 42 s = 74 s = 60 s + 14 s = 1 min 14 s
                                                                                                                 28     32
                    Step 2.  Add the minutes.                                                               +    24     42
                              1 min + 28 min + 24 min = 53 min                                                   53     14

                    example 2. Add 16 hours 24 minutes 18 seconds and 31 hours 48 minutes 52 seconds.

                    Solution.

                    Step 1.  Add the seconds.
                              18 s + 52 s = 70 s = 60 s + 10 s = 1 min 10 s                               h     min     s

                    Step 2.  Add the minutes.                                                              1      1
                              1 min + 24 min + 48 min  = 73 min                                           16     24     18

                                                            = 60 min + 13 min = 1 h 13 min           +    31     48     52
                    Step 3.  Add the hours.                                                               48     13     10

                              1 h + 16 h + 31 h = 48 h

                    example 3. Subtract 22 minutes 32 seconds from 30 minutes 18 seconds.
                    Solution. Write the times in columns correctly and then subtract.

                    Step 1.  Subtract the seconds.

                              Since 18 < 32, regroup minutes and seconds.                                       min     s
                                                                                                                 29     78
                              So, 30 min 18 s = 29 min 60 s + 18 s = 29 min 78 s                                30      18

                              Now, 78 s – 32 s = 46 s                                                       –    22     32
                                                                                                                  7     46
                    Step 2.  Subtract the minutes. 29 min – 22 min = 7 min

                    example 4. Subtract:
                                 a  4 hours 44 min from 6 hours 14 min                 b.  13 hours 28 min from 1 day
                    Solution. We write the measures of time in the appropriate columns and regroup to
                    subtract.

                                 a.  6 h 14 min = 5 h 74 min  b.                       1 day = 24 h = 23 h 60 min
                                                   h    min                                              h    min
                                                   5      74                                             23    60
                                                   6      14                                            24     00

                                              –    4     44                                         –    13    28
                                                    1    30                                             10     32

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