5th Grade · Number & Operations in Base Ten
5.NBT.B.5: Fluently multiply larger numbers, like 213 × 32
5.NBT.B.5 is a 5th grade Common Core math standard in Number & Operations in Base Ten. Here’s what it really covers, and how you can help your students learn it.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
The standard
Fluently multiply multi-digit whole numbers using the standard algorithm.
In plain words
Fluently multiply larger numbers, like 213 × 32.
Sample questions from student practice
These questions from Bobby's Math Club are the kinds of questions your students will see. You can try answering them to see what a student might see.
Question 1 of 3
Each apple tree in an orchard grows 30 apples. The orchard has 120 trees. How many apples do the trees grow?
- 36,000
- 3,600
- 150
Where students can get stuck
- Forgetting the placeholder zero, so 213 × 32 becomes 426 + 639 = 1,065 instead of 6,816.
- Mixing up the small carried digits, adding one from multiplying by 2 into the row for multiplying by 30.
- Misaligning the columns of partial products, so tens sit under hundreds and the total is far off.
Effective teaching strategies
- Ask students to estimate 213 × 32 by rounding first, then compare the exact product with the estimate to catch answers that are far off.
- Show the written method beside an area model, so students see that the second row means 213 × 30 and why it begins with a placeholder zero.
- Give students grid paper so each digit sits in its own column, and have them say each digit’s value aloud as they carry.
Units that teach this standard
Find where 5.NBT.B.5 lands in the program you teach. Each unit has a guide written for families. Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence.
Bridges in Mathematics
enVision Mathematics
Eureka Math²
Everyday Mathematics
i-Ready Classroom Mathematics
Illustrative Mathematics
Math Expressions
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Families can read Multiplying big numbers, like 213 × 32 for a plain-language look at this skill, with three questions to try together and ideas for helping at home.
Help every student practice place value at home
In Bobby's Math Club, students practice at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free for every family.
See how it works for teachers
Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.