1.NBT.2.c: Understanding Multiples of 10
I can understand that the two digits of a two-digit number represent amounts of tens and ones, including multiples of 10.
What Your Child Needs to Know
This standard helps your child understand special two-digit numbers called multiples of 10 (like 10, 20, 30, 40, 50, 60, 70, 80, 90). These numbers are important because they have zero ones and only tens. First graders learn to recognize that 30 means "3 tens and 0 ones" and that these numbers follow a predictable pattern. This understanding builds a strong foundation for place value and helps with mental math strategies.
Real World Practice
Visual models and hands-on activitiesVisual Models
Base-10 Blocks: Use base-10 blocks to show multiples of 10. Show that 40 is 4 ten-rods with no unit cubes.
Ten Frames: Create multiple ten frames to represent multiples of 10. Show 30 as 3 filled ten frames.
Bundling Sticks: Bundle groups of 10 popsicle sticks to show multiples of 10. 50 = 5 bundles of 10.
Number Line Jumps: Use a number line to show jumps of 10: 10, 20, 30, 40, 50...
Everyday Activities
Counting by 10s Hunt: Find groups of 10 items around the house (10 spoons, 20 crackers, 30 blocks) and count by tens.
Dime Counting: Use dimes to represent multiples of 10. Show that 4 dimes = 40 cents = 4 tens.
Egg Carton Math: Use egg cartons (which hold 10 or 12) to practice grouping by tens and understanding multiples.
Skip Counting Songs: Sing counting by 10s songs while clapping or marching to reinforce the pattern.
Quick Checks
Strategies and quick activitiesStrategies When Your Child Struggles
Start with Concrete Objects: Use actual groups of 10 items before moving to abstract numbers.
Emphasize the Pattern: Point out that multiples of 10 always end in 0 and follow a counting pattern.
Connect to Counting: Practice counting by 10s regularly: 10, 20, 30, 40, 50...
Use Money: Dimes are perfect for understanding multiples of 10 since each dime = 10 cents.
5-Minute Practice Activities
Multiple of 10 Race: Call out a multiple of 10 and have your child quickly show it with their fingers (3 for 30, 7 for 70).
What Comes Next?: Start a pattern (10, 20, 30...) and have your child continue it.
Tens and Ones Sort: Give your child number cards and have them sort multiples of 10 from other numbers.
Quick Draw: Call out a multiple of 10 and have your child quickly draw that many groups of 10 dots.
Check Progress
Track improvementDevelopmental Milestones
Beginning: Can count by 10s to 50 with support and recognizes that these numbers are "special."
Developing: Counts by 10s to 100 independently and can identify multiples of 10 when shown various numbers.
Proficient: Understands that multiples of 10 have zero ones and can explain why (e.g., "40 has 4 tens and 0 ones").
Advanced: Can work backwards from 100 by 10s and solve simple problems involving multiples of 10.
What to Look For
Pattern Recognition: Your child notices that multiples of 10 all end in 0.
Skip Counting: Can count by 10s fluently without needing to count by 1s first.
Place Value Understanding: Knows that 60 means "6 tens and 0 ones."
Visual Recognition: Can quickly identify multiples of 10 when shown with base-10 blocks or other visual models.
Differentiation
Support for all learning levelsBelow Grade Level
Focus on counting by 10s to 50 with concrete objects. Use visual models and hands-on activities. Practice recognizing multiples of 10 among other numbers.
Download Practice WorksheetAt Grade Level
Practice counting by 10s to 100 and understanding that multiples of 10 have zero ones. Work with place value representation of these special numbers.
Download Grade Level WorksheetAbove Grade Level
Extend to counting by 10s beyond 100, working backwards from 100, and solving word problems involving multiples of 10.
Download Challenge Worksheet