Concept 6 of 7
Imperial Units: Inches, Feet, Yards, Miles
Today's big idea
Imperial links are not powers of 10: 12 in, then 3 ft, then 1,760 yd, and 16 oz.
Nothing here jumps by 10, so read the link off the row before you multiply.
How it works
👀 What's going on?
Not every country counts in metres. How tall is a door in London? The answer comes back as 6 ft 8 in, and a race there may be run in miles.
💡 Here's the trick
Look at the chart above. Imperial steps are not powers of 10, so each pair carries its own number. Length runs 12, then 3, then 1,760, and weight runs 16.
🪄 How to do it
- 1.Find the pair of units on the chart above.
- 2.Read the number that links them.
- 3.Multiply going down, divide going up.
✍️ Try it
Change 11 ft into inches. Then: change 4 yd into feet.
Each foot holds 12 inches, so 11 × 12 = 132 inches. Each yard holds 3 feet, so 4 × 3 = 12 feet.
⚠️ Watch out
You might be thinking imperial works like metric, with a tidy 10 between units. It does not. A foot holds 12 inches, so 1.5 ft is 18 in and never 15 in.
🌟 Why this matters
Screen sizes, water pipes and bicycle rims are still sold in inches. Height in many countries is still given in feet, so the 12 link is worth knowing.
Exam tip: Jot the link you need at the top of your rough work before you start.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“A string is 3 ft 6 in long. How many INCHES is that?”
- 1
Recall the fact
1 ft = 12 in. 📐
- 2
Convert the feet part
3 ft × 12 = 36 in.
- 3
Add the leftover inches
36 + 6
- 4
Answer ✓
3 ft 6 in = 42 in
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Imperial doesn't use a ×10 ladder — multiply big → small, divide small → big.
IMPERIAL · ROUND 1 OF 3
4 ft → inches
Quick check
✅ VERIFICATION
A plank is 2 ft 9 in long. How many INCHES is that?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Measurement Word Problems
Same unit on every line, then arithmetic.