Mathematics
Grade 4
15 min
Multiply a 2-digit number by a larger number: word problems
Multiply a 2-digit number by a larger number: word problems
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Introduction & Learning Objectives
Learning Objectives
Identify the necessary information in a multi-step word problem.
Determine that multiplication is the correct operation to solve 'total' or 'in all' scenarios.
Accurately set up a multiplication problem involving a 2-digit number and a larger number (3- or 4-digits).
Solve multiplication problems using the standard algorithm or an area model.
Use estimation to check if their final answer is reasonable.
Write a final answer that includes the correct units based on the word problem's context.
Have you ever wondered how many bricks it takes to build a giant LEGO castle? 🏰 Let's learn the math to figure it out!
In this lesson, you will become a math detective, pulling clues (numbers) from stories to solve real-world multiplicat...
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Key Concepts & Vocabulary
TermDefinitionExample
ProductThe answer you get when you multiply two or more numbers together.In 125 x 12 = 1,500, the number 1,500 is the product.
FactorsThe numbers that are being multiplied together to get a product.In 125 x 12 = 1,500, the numbers 125 and 12 are the factors.
MultiplierThe factor that you are multiplying by. In our problems, this will usually be the 2-digit number.In the problem 350 x 24, the number 24 is the multiplier.
Partial ProductsThe results you get when you multiply parts of the numbers. You add these together to get the final product.To solve 142 x 13, you find the partial products of 142 x 3 (which is 426) and 142 x 10 (which is 1420).
KeywordsWords in a story problem that give you clues about which math operation to use.Words like 'each,' 'ev...
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Core Formulas
Standard Algorithm for Multiplication
(ABC) \times (DE) = (ABC \times E) + (ABC \times D0)
This is a step-by-step way to multiply. First, multiply the top number by the ones digit of the bottom number. Then, multiply the top number by the tens digit of the bottom number, remembering to add a placeholder zero. Finally, add the two partial products together.
Area Model for Multiplication
(A+B) \times (C+D) = (A \times C) + (A \times D) + (B \times C) + (B \times D)
This visual method breaks down both numbers into their place values (e.g., 125 becomes 100 + 20 + 5). You draw a box, multiply each part, and then add all the smaller products together to get the final answer.
4 more steps in this tutorial
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Challenging
Store A sells 25 boxes of crayons with 128 crayons in each box. Store B sells 35 boxes of crayons with 96 crayons in each box. Which statement is true?
A.Store A sells 160 more crayons than Store B.
B.Both stores sell the same number of crayons.
C.Store B sells 160 more crayons than Store A.
D.Store B sells 150 more crayons than Store A.
Challenging
A powerful machine can print 1,250 newspapers in one hour. If the machine runs for a full 12-hour day, but 500 of the newspapers are misprinted and must be recycled, how many usable newspapers are produced?
A.15,500 newspapers
B.14,500 newspapers
C.15,000 newspapers
D.1,750 newspapers
Challenging
A company needs to ship approximately 8,000 toy soldiers. Their factory can produce 385 soldiers per day. Which is the most reasonable estimate for how many days it will take to produce enough soldiers?
A.15 days
B.20 days
C.25 days
D.30 days
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