SUBTRACTION OF DENOMINATE NUMBERS

1. Arrange the units in column, start with the highest unit at the left end.
2. Subtract starting at the smallest unit at the right.
3. Take one unit of the next higher order if you cannot deduct.
4. Reduce the answer to the higher denominations if necessary.

Ex. Find the difference of 24 yards 5 feet 7 inches and 21 yards 5 feet 10 inches.

Solution:

Step 1. Arrange the units in column.

          24 yd 5 ft 7 in
-        21 yd 5 ft 10 in

Step 2. Subtract starting from the lowest unit.

7 in - 10 in (cannot be done for being whole numbers)
So, take 1 ft from 5 ft leaving 4 ft.

Step 3. Change the foot borrowed to inches.

1 ft = 12 inches

Step 4. Regroup the inches in the minuend.

12 inches + 7 inches = 19 inches

Step 5. Subtract the inches.

      24 yd 4 ft 19 in
-    21 yd 5 ft 10 in
                       9 in

Step 6. Subtract the feet.

4ft - 5ft (cannot be done for being a whole numbers).
So, take 1 yard from 24 yards leaving 23 yards.

Step 7. Change the yard borrowed to feet.

1 yard = 3 ft

Step 8. Regroup the feet in the minuend.

4 ft + 3 ft = 7 ft

Step 9. Subtract the feet and yard.

         23 yd 7 ft 19 in
-       21 yd 5 ft 10 in

ANSWER: 2 yd 2ft 9 in

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