Mathematics
Grade 4
15 min
Add and subtract mixed customary units
Add and subtract mixed customary units
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1
Introduction & Learning Objectives
Learning Objectives
Identify common customary units for length, weight, and capacity.
Recall key conversion factors, such as 1 foot = 12 inches and 1 pound = 16 ounces.
Add two mixed customary unit measurements, including regrouping smaller units into larger units.
Subtract two mixed customary unit measurements, including regrouping (borrowing) from larger units to smaller units.
Solve one-step word problems involving the addition and subtraction of mixed customary units.
If you bake a cake that needs 2 pounds 8 ounces of flour and your friend bakes one that needs 1 pound 10 ounces, how much flour do you need altogether? Let's find out! 🎂
In this lesson, you will learn how to add and subtract measurements that use more than one unit, like feet and inches. This is a very...
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Key Concepts & Vocabulary
TermDefinitionExample
Customary UnitsThe system of measurement most commonly used in the United States. It includes units like inches, feet, yards, ounces, pounds, cups, and gallons.A ruler measures length in inches and feet.
Mixed UnitsA measurement that uses two or more related units.A person's height is 4 feet 11 inches. A bag of potatoes weighs 5 pounds 4 ounces.
ConversionChanging a measurement from one unit to another equivalent unit.Converting 12 inches into 1 foot.
Regrouping (Carrying)In addition, this is when you combine smaller units to make a larger unit.If you have 15 inches, you can regroup it as 1 foot and 3 inches.
Regrouping (Borrowing)In subtraction, this is when you break down a larger unit into smaller units to make subtraction possible.To subtract 9 inches from 3...
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Core Formulas
Length Conversions
1 \text{ foot (ft)} = 12 \text{ inches (in)} \newline 1 \text{ yard (yd)} = 3 \text{ feet (ft)}
Use these rules when you need to regroup inches into feet or borrow a foot to get more inches.
Weight Conversions
1 \text{ pound (lb)} = 16 \text{ ounces (oz)}
Use this rule when your ounces add up to 16 or more, or when you need to borrow from the pounds column to subtract ounces.
Capacity Conversions
1 \text{ gallon (gal)} = 4 \text{ quarts (qt)} \newline 1 \text{ quart (qt)} = 2 \text{ pints (pt)}
Use these rules when adding or subtracting liquid measurements.
4 more steps in this tutorial
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Challenging
A baker has a 10 lb bag of sugar. She uses 3 lb 12 oz for a batch of cookies and 2 lb 8 oz for a cake. How much sugar is left?
A.5 lb 4 oz
B.6 lb 4 oz
C.3 lb 12 oz
D.4 lb 12 oz
Challenging
A painter has a full 5-gallon can of paint. He uses 2 gal 3 qt on Monday and 1 gal 2 qt on Tuesday. How much paint is left in the can?
A.4 gal 1 qt
B.1 gal 1 qt
C.0 gal 3 qt
D.1 gal 3 qt
Challenging
Look at this student's work for subtracting 9 ft 2 in - 3 ft 7 in.
Step 1: Borrow 1 ft from 9 ft, leaving 8 ft.
Step 2: Add 10 inches to 2 inches, making it 12 inches.
Step 3: Subtract 12 in - 7 in = 5 in.
Step 4: Subtract 8 ft - 3 ft = 5 ft.
Answer: 5 ft 5 in.
Which step contains the error?
A.Step 2
B.Step 1
C.Step 3
D.Step 4
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