2nd Grade · Number & Operations in Base Ten
2.NBT.A.1: Understand that the three digits of a three-digit number represent amounts of hundreds, tens, and ones
2.NBT.A.1 is a 2nd 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
Understand that the three digits of a three-digit number represent amounts of hundreds, tens, and ones; e.g., 706 equals 7 hundreds, 0 tens, and 6 ones. Understand the following as special cases: a. 100 can be thought of as a bundle of ten tens called a "hundred." b. The numbers 100, 200, 300, 400, 500, 600, 700, 800, 900 refer to one, two, three, four, five, six, seven, eight, or nine hundreds (and 0 tens and 0 ones).
In plain words
Understand that the three digits of a three-digit number represent amounts of hundreds, tens, and ones.
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
How many hundreds are in 300?
- 3
- 30
- 300
Where students can get stuck
- Treating zero as nothing at all, writing 76 for seven hundred six because the tens place seems empty.
- Reading the 4 in 482 as four, not four hundred, and building it with 4 single blocks.
- Missing that 10 tens make 1 hundred, so being puzzled that 13 tens and 130 are the same amount.
Effective teaching strategies
- Build 706 with base-ten blocks, using 7 flats, no rods, and 6 unit cubes, and have students say “7 hundreds, 0 tens, 6 ones” so a zero stays a placeholder.
- Have students trade 10 rods for 1 flat and say that 10 tens make 1 hundred, then build 12 tens and show that it is the same amount as 120.
- Ask students to point to each digit in 538 and name its value as 5 hundreds, 3 tens, and 8 ones, and to show which blocks stand for the 5.
Units that teach this standard
Find where 2.NBT.A.1 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
Reveal Math
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Families can read Hundreds, tens, and ones in numbers like 706 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.