4th Grade · Number & Operations in Base Ten
4.NBT.B.5: Multiply larger numbers, like 3,045 × 8 and 64 × 38
4.NBT.B.5 is a 4th 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
Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.
In plain words
Multiply larger numbers, like 3,045 × 8 and 64 × 38.
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 6
Beads come in bags of 125. Jamal buys 6 bags to make bracelets. How many beads does he get?
- 620
- 750
- 625
Where students can get stuck
Multiply large numbers by a one-digit number.
- Writing each digit’s product side by side, so 48 × 7 becomes 2,856 instead of 336.
- Losing track of the zero in a number like 3,045, multiplying the 3 as 300 and getting 2,760 instead of 24,360.
- Adding the leftover digits instead of multiplying them, so 427 × 6 becomes 2,400 + 27 = 2,427 instead of 2,562.
Multiply two two-digit numbers.
- Multiplying only the matching places, so 64 × 38 becomes 1,800 + 32 = 1,832, missing 60 × 8 and 4 × 30.
- Treating tens as ones inside a part, writing 60 × 30 as 180 instead of 1,800.
- Getting each part right but adding them wrongly, such as lining up 1,800, 480, 120, and 32 by their left edges.
Effective teaching strategies
- Show 64 × 38 on an area model split into 60 and 4 by 30 and 8, and have students find all four partial products before adding.
- Ask students to say 60 × 30 as 6 tens times 3 tens, so they see 18 hundreds, or 1,800, and not 180.
- Break 3,045 × 8 into 3,000 × 8, 40 × 8, and 5 × 8, and have students add the three products with the places lined up.
Units that teach this standard
Find where 4.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
Everyday Mathematics
i-Ready Classroom Mathematics
Illustrative Mathematics
Math Expressions
Reveal Math
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Each skill has its own guide for families, with a plain-language look at the skill, 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.