ADDITION OF DENOMINATE NUMBERS

1. Arrange the units in column, start with the highest unit at the left end.

2. Add all columns.
3. Reduce the answer to the higher denomination if necessary.

Ex. Combine 8hrs 44 min 31 sec and 9 hrs 47 min 53 sec.

Solution:

Step 1. Arrange the units and add:
           8hrs 44 min 31 sec
+         9 hrs 47 min 53 sec
         17 hrs 91 min 84 sec

Step 2. Reduce the answer.

There are 60 sec in 1 min. So, 84 sec = 1 min 24 sec.
There are 60 min in 1 hr. So, 92 min = 1 hr 32 min.

           8hrs 44 min 31 sec
+         9 hrs 47 min 53 sec
        17 hrs 91 min 84 sec

= 17 hrs 91 min 1 min + 24 sec

= 17 hrs 91 min + 1 min 24 sec

= 17 hrs 92 min 24 sec
 
= 17 hrs 1hr + 32 min 24 sec

= 17 hrs 1hr + 32 min 24 sec

Answer: 18 hrs 32 min 24 sec