🇺🇸 CCSS Math · Grade 5

5.NBT.B.5: Multi-digit multiplication (standard algorithm)

5.NBT.B.5 explained: fluent multi-digit multiplication with the standard algorithm, why each partial product works, common errors and practice.

Common Core standard CCSS.Math.Content.5.NBT.B.5

Fluently multiply multi-digit whole numbers using the standard algorithm.

Grade
Grade 5
Domain
Number & Operations in Base Ten (NBT)
Cluster
Perform operations with multi-digit whole numbers and with decimals to hundredths

Official wording from the Common Core State Standards for Mathematics (© 2010 National Governors Association Center for Best Practices and Council of Chief State School Officers). View on thecorestandards.org

What 5.NBT.B.5 means

By the end of fifth grade, students are expected to multiply multi-digit whole numbers quickly and accurately using the standard algorithm, the vertical method that multiplies by one digit of the bottom factor at a time and records regrouped values above. Fluency here means efficient, accurate and flexible, not just fast.

The algorithm is a compressed form of the partial products students used in fourth grade. In 346 × 27, the first row is 346 × 7 = 2,422 and the second row is 346 × 20 = 6,920, which is why a zero is placed in the ones column before multiplying by the 2. Adding the rows gives 9,342. Students who understand this can explain each step in place value language, spot an answer that is far too small, and estimate first (about 350 × 30 = 10,500) to judge whether the result is reasonable. That habit of estimating first is what separates fluent multipliers from students who only follow steps.

Students should be able to

  • Multiply a three- or four-digit number by a one- or two-digit number using the standard algorithm.
  • Explain why the second partial product starts with a zero in the ones place.
  • Regroup correctly and add carried digits after multiplying, not before.
  • Estimate a product by rounding to check the reasonableness of an answer.
  • Solve multi-step word problems that involve multi-digit multiplication.

Common misconceptions

Forgetting the placeholder zero

When multiplying by the tens digit, students who omit the zero record 346 × 2 instead of 346 × 20, and the final product is far too small.

Adding the carried digit before multiplying

In 47 × 6, the carried 4 from 7 × 6 = 42 must be added after 4 × 6 is found (24 + 4 = 28), not added to the 4 before multiplying.

Leaving old carried digits in place

Regrouped digits from the first row confuse the second row. Crossing them out or using a fresh line for each partial product prevents this.

Misaligning partial products

If digits drift out of their columns, the final addition is wrong even when every multiplication fact is right. Grid paper helps keep columns straight.

Worked example: 346 × 27

Multiply 346 × 27 using the standard algorithm and check with an estimate.

  1. Estimate first: 346 is about 350 and 27 is about 30, so the product should be near 10,500.
  2. Multiply 346 by 7: 6 × 7 = 42 (write 2, carry 4), 4 × 7 + 4 = 32 (write 2, carry 3), 3 × 7 + 3 = 24. The first row is 2,422.
  3. Multiply 346 by 20: write a 0 in the ones place, then 346 × 2 = 692, so the second row is 6,920.
  4. Add the rows: 2,422 + 6,920 = 9,342, which is close to the estimate.

Answer: 346 × 27 = 9,342.

Teaching 5.NBT.B.5

Put a partial products area model next to the standard algorithm for the same problem and ask students to match each row of the algorithm to regions of the area model. This keeps the place value meaning visible while students build speed.

Fluency is often assessed with straight computation items, such as 1,208 × 36, and through word problems where multiplication is one step of several. Short, frequent practice is more effective than long sets.

6 practice questions

Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.

Score: 0 / 6(0 of 6 checked)
  1. 1.

    Calculate 423 × 6.

    Answer and explanation

    Answer: 2538 (also accepted: 2,538)

    3 × 6 = 18 (write 8, carry 1). 2 × 6 + 1 = 13 (write 3, carry 1). 4 × 6 + 1 = 25. The product is 2,538.

  2. 2.

    Calculate 58 × 34.

    Answer and explanation

    Answer: 1972 (also accepted: 1,972)

    58 × 4 = 232 and 58 × 30 = 1,740. Adding gives 232 + 1,740 = 1,972.

  3. 3.

    What is 2,105 × 13?

    Question 3 options
    Answer and explanation

    Answer: C) 27,365

    2,105 × 3 = 6,315 and 2,105 × 10 = 21,050. 6,315 + 21,050 = 27,365.

  4. 4.

    When multiplying 517 × 42 with the standard algorithm, what is the second partial product?

    Question 4 options
    Answer and explanation

    Answer: B) 20,680

    The second row is 517 × 40, because the 4 is in the tens place. 517 × 40 = 20,680.

  5. 5.

    A theater has 28 rows with 145 seats in each row. How many seats are there?

    Answer and explanation

    Answer: 4060 (also accepted: 4,060, 4060 seats, 4,060 seats)

    145 × 8 = 1,160 and 145 × 20 = 2,900. 1,160 + 2,900 = 4,060 seats.

  6. 6.

    Which estimate is the most useful check for 692 × 48?

    Question 6 options
    Answer and explanation

    Answer: D) 700 × 50 = 35,000

    Rounding each factor to its nearest friendly number gives 700 × 50 = 35,000. The exact product, 33,216, is close to this.

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FAQ

Does 5.NBT.B.5 require the standard algorithm only?

It sets the standard algorithm as the fluency goal. Students may still use area models or partial products to understand or check, but by the end of the year they should be fluent with the algorithm.

How large are the numbers in fifth grade multiplication?

The standard says multi-digit whole numbers. In practice that is usually up to four-digit by two-digit products, which are big enough to need the full algorithm.

More grade 5 Number & Operations in Base Ten standards

5.NBT.A.1: Place value: ten times and one tenth5.NBT.A.2: Powers of 10 and exponents5.NBT.A.3: Reading, writing and comparing decimals5.NBT.A.4: Rounding decimals5.NBT.B.6: Division with two-digit divisors5.NBT.B.7: Operations with decimals to hundredths
More practice on this topic →All Grade 5 math standards →Standards home →