Worked examples
Two examples
Example 1
5 ft 8 in + 2 ft 7 in = ? ft ? in
- Add each part: 7 feet and 15 inches.
- 15 inches is more than 12: trade 12 inches for 1 foot. 8 feet 3 inches.
Answer: 8 ft 3 in
Example 2
7 ft 2 in − 3 ft 9 in = ? ft ? in
- You cannot take 9 inches from 2, so borrow 1 foot = 12 inches: 6 ft 14 in.
- Subtract: 6 − 3 = 3 feet, 14 − 9 = 5 inches.
Answer: 3 ft 5 in
Where this is taught: Quiz 26: Units and Conversions, “The conversions on this page”
The drill
Ten problems
How many:
Type the two numbers in order, like 8 ft 3 in (or just 8, 3). Then press Check my answers at the bottom.Write each ratio on the line, like 3 : 4. The answer key, with the reasoning, is on the last page.