Convert between Feet and Inches in Context - ISEE Lower Level Mathematics Achievement

SECTION 1

Why Do We Need Feet and Inches?

People have been measuring things for thousands of years. Long ago, they used body parts like thumbs and feet to measure length. That's actually how feet and inches got their names!

The word "inch" comes from a Latin word meaning "one-twelfth." That's because there are 12 inches in every foot. Let's look at how these units developed over time.

3000 BC • Ancient Egypt

Egyptians used body parts to measure. A "cubit" was the length from elbow to fingertip!

1100s • King Henry I of England

The king declared that a "yard" was the distance from his nose to his thumb. Feet and inches were set to fractions of a yard.

1824 • British Weights and Measures Act

England made the foot an official unit of measurement. One foot equals exactly 12 inches.

Today • Used in the United States

The United States still uses feet and inches every day — to measure height, room sizes, and so much more!

On the ISEE, you'll see problems that ask you to switch between feet and inches. Knowing the magic number — 12 — is the key. Let's learn how!

SECTION 2

Core Principles: The Big Ideas

Before we start converting, let's learn the big ideas. These three rules will help you solve any feet-and-inches problem!

The Magic Number Is 12

There are always 12 inches in 1 foot. This never changes!

Multiply to Go Bigger → Smaller

To change feet into inches, multiply by 12. You're breaking a big unit into smaller pieces.

Divide to Go Smaller → Bigger

To change inches into feet, divide by 12. You're grouping small pieces into a big unit.

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KEY TAKEAWAY

Think of feet like pizza boxes and inches like slices. Each box has 12 slices. If you have 3 boxes, multiply 3 × 12 to find 36 total slices. If you have 24 slices, divide 24 ÷ 12 to find you can fill 2 boxes!

SECTION 3

See It: Feet and Inches on a Ruler

Let's look at a picture that shows how feet and inches relate. Notice how 12 small inch marks fit inside each foot!

This ruler shows that 12 inch marks fit perfectly inside 1 foot. The blue rule at the bottom reminds you to multiply when going from feet to inches, and divide when going from inches to feet.

Look at the ruler above. Count the marks from 0 to 12. That's one full foot! If you lined up two rulers end to end, you'd have 2 feet = 24 inches.

SECTION 4

The Math: Two Simple Formulas

You only need two formulas for these problems. Let's learn them both!

FEET TO INCHES

Inches = Feet × 12

When you know the number of feet and want to find inches, multiply by 12. Example: 3 feet × 12 = 36 inches.

INCHES TO FEET

Feet = Inches ÷ 12

When you know the number of inches and want to find feet, divide by 12. Example: 60 inches ÷ 12 = 5 feet.

MIXED MEASUREMENTS

Total inches = (Feet × 12) + Extra inches

Sometimes a measurement is given as feet AND inches, like 4 feet 3 inches. Convert the feet part first (4 × 12 = 48), then add the leftover inches (48 + 3 = 51 inches total).

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ISEE Test Tip!

On the ISEE, always check the units in the question AND the answer choices. If the question asks for inches, make sure your answer is in inches. If it asks for feet, make sure your answer is in feet. Many wrong answers come from forgetting this!

SECTION 5

Handy Conversion Chart

Knowing some common conversions by heart saves you time on test day. Let's study this chart. You don't need to memorize every row — just understand the pattern!

Feet	× 12	= Inches
1 foot	1 × 12	12 inches
2 feet	2 × 12	24 inches
3 feet	3 × 12	36 inches
4 feet	4 × 12	48 inches
5 feet	5 × 12	60 inches
6 feet	6 × 12	72 inches

Common feet-to-inches conversions

This flowchart shows the two directions of conversion. Going from feet to inches? Multiply by 12. Going from inches to feet? Divide by 12. The worked example shows how to handle a mixed measurement like 4 feet 5 inches.

Here's a helpful pattern to notice. Each time you add one more foot, you add 12 more inches. So 1 foot = 12, 2 feet = 24, 3 feet = 36, and so on. It's like counting by 12s!

SECTION 6

Worked Example: Step by Step

Let's walk through a problem like one you might see on the ISEE. Follow each step carefully!

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Sample Problem

Maria's bookshelf is 5 feet 7 inches tall. Her brother says it is more than 70 inches tall. Is he correct? How many inches tall is the bookshelf?

Solving: Convert 5 feet 7 inches to inches

1
Step 1 — Identify the parts

The bookshelf is 5 feet and 7 inches. We need to convert the feet part to inches, then add the extra inches.

Feet part: 5 | Extra inches: 7
2
Step 2 — Convert the feet to inches

Use the formula: Inches = Feet × 12. So 5 × 12 = 60 inches. The 5-foot part equals 60 inches.

5 feet = 60 inches
3
Step 3 — Add the leftover inches

Now add the 7 extra inches: 60 + 7 = 67 inches.

60 + 7 = 67 inches
4
Step 4 — Answer the question

The bookshelf is 67 inches tall. Is 67 more than 70? No! Maria's brother is not correct. The bookshelf is 3 inches shorter than 70 inches.

67 inches (less than 70)

SECTION 7

Strengths and Common Mistakes

Let's look at what makes these problems easy — and the tricky parts where students sometimes slip up!

✅ What Makes It Easy	⚠️ Common Mistakes
Only one number to remember: 12	Using 10 instead of 12 (metric mix-up)
Multiply and divide are the only operations	Multiplying when you should divide, or vice versa
Answer choices on the ISEE are in order, so you can estimate	Forgetting to add extra inches in a mixed measurement
You can check your work by doing the opposite operation	Not reading whether the answer should be in feet or inches

Strengths vs. common mistakes

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REMEMBER THIS TRICK!

Ask yourself: "Am I going from a big unit to a small unit, or small to big?" Big to small (feet to inches) means your answer should be a BIGGER number, so multiply. Small to big (inches to feet) means your answer should be a SMALLER number, so divide. If your answer seems backwards, you probably picked the wrong operation!

SECTION 8

Connecting to Other Measurement Conversions

Feet and inches is just one pair of measurement units. The same thinking works for other conversions you might see on the ISEE!

Conversion	Magic Number	How It's Similar
Feet ↔ Inches	12	This is the one we just learned!
Yards ↔ Feet	3	1 yard = 3 feet. Multiply or divide by 3.
Yards ↔ Inches	36	1 yard = 36 inches. That's 3 × 12!

Length conversions in the U.S. customary system

The strategy is always the same. Find the magic number that connects the two units. Then multiply to go from a bigger unit to a smaller one, or divide to go the other way. You've got this!

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Looking Ahead

As you move to higher-level math, you'll also convert metric units (meters and centimeters) and even switch between systems. The multiply-and-divide strategy you're learning now will help you with all of those!

SECTION 9

Practice Problems

Time to test your skills! Try each problem on your own before peeking at the answer. Remember — on the real ISEE, always answer every question, even if you need to guess!

Question 1: CONCEPTUAL

How many inches are in 1 foot?

A. 6
B. 10
C. 12
D. 24

Show answer (C)

The correct answer is C (12). There are exactly 12 inches in 1 foot. This is the key fact for every feet-and-inches problem! A (6) is only half a foot. B (10) is a common mistake — people sometimes mix up 10 (from the metric system) with 12. D (24) is the number of inches in 2 feet, not 1 foot.

Question 2: BASIC CALCULATION

A table is 4 feet long. How many inches long is it?

A. 36 inches
B. 40 inches
C. 48 inches
D. 52 inches

Show answer (C)

The correct answer is C (48 inches). To convert feet to inches, multiply: 4 × 12 = 48 inches. A (36) is what you'd get if you multiplied 3 × 12 — that's only 3 feet. B (40) is the mistake of multiplying 4 × 10 instead of 4 × 12. D (52) would come from an arithmetic error.

Question 3: INTERMEDIATE

Sam is 3 feet 8 inches tall. How tall is Sam in inches?

A. 38 inches
B. 44 inches
C. 46 inches
D. 56 inches

Show answer (B)

The correct answer is B (44 inches). First convert the feet: 3 × 12 = 36 inches. Then add the extra 8 inches: 36 + 8 = 44 inches. A (38) is the common mistake of just putting the 3 and 8 together as "38." C (46) would come from an addition error. D (56) might result from using the wrong multiplication fact.

Question 4: APPLIED

A piece of ribbon is 84 inches long. Emma needs to cut it into lengths that are each 1 foot long. How many 1-foot pieces can she cut?

A. 6 pieces
B. 7 pieces
C. 8 pieces
D. 12 pieces

Show answer (B)

The correct answer is B (7 pieces). Each 1-foot piece is 12 inches. Divide: 84 ÷ 12 = 7. So she can cut 7 pieces. A (6) comes from dividing incorrectly — 6 × 12 = 72, not 84. C (8) would mean 96 inches, which is too much. D (12) confuses the number of inches in a foot with the answer.

Question 5: CRITICAL THINKING

Jake's dog is 2 feet 3 inches tall. His cat is 15 inches tall. How much taller is the dog than the cat?

A. 10 inches
B. 12 inches
C. 15 inches
D. 24 inches

Show answer (B)

The correct answer is B (12 inches). First, convert the dog's height to inches: 2 × 12 = 24, plus 3 = 27 inches. The cat is 15 inches. Subtract: 27 − 15 = 12 inches. The dog is 12 inches (or 1 foot) taller. A (10) results from a subtraction error. C (15) is just the cat's height, not the difference. D (24) is just the inches in 2 feet, ignoring the extra 3 inches and the subtraction step.

SUMMARY

Let's Review!

Summary

You learned the key fact: 1 foot = 12 inches. To convert feet to inches, multiply by 12. To convert inches to feet, divide by 12. For mixed measurements like 3 feet 5 inches, convert the feet first, then add the extra inches.

On the ISEE, always check whether the question wants your answer in feet or inches. Remember that going from a bigger unit to a smaller unit makes a bigger number (multiply), and going from a smaller unit to a bigger unit makes a smaller number (divide). You've got this — great job learning today!