2.NBT.5: Fluently Add and Subtract Within 100

I can fluently add and subtract within 100 using strategies based on place value.

What Your Child Needs to Know

This standard focuses on helping your child become quick and accurate with addition and subtraction of numbers up to 100. Students will learn strategies based on place value, such as breaking numbers apart by tens and ones, to solve problems efficiently.

This standard builds on previous addition and subtraction skills with smaller numbers and prepares your child for working with larger numbers in future grades. Mastering these skills will help your child develop computational fluency, which is essential for more complex math concepts.

Real World Practice

Visual models and hands-on activities

Visual Models to Use

  • Place Value Blocks - Use base-ten blocks to represent tens and ones when adding and subtracting. This helps your child visualize regrouping (carrying and borrowing).
  • Place Value Chart - A chart with columns for tens and ones that helps your child organize numbers by place value when adding and subtracting.
  • Open Number Line - A number line without all numbers marked that helps your child visualize jumps of tens and ones when adding and subtracting.
  • Hundred Chart - A grid of numbers from 1-100 that helps your child see patterns when adding or subtracting 10 or finding numbers that are 10 more or 10 less.

Everyday Activities

1. Grocery Store Math

When shopping, have your child add up the prices of items (keeping numbers under 100) or calculate change using place value strategies.

2. Score Keeper

During family games, make your child the scorekeeper. They'll practice adding and subtracting two-digit numbers as scores change.

3. Daily Addition and Subtraction Challenge

Create a daily challenge with two-digit addition and subtraction problems. Track progress on a chart to show improvement.

4. Place Value Card Game

Use playing cards to create two-digit numbers. Players take turns drawing cards to create numbers, then add or subtract them using place value strategies.

Quick Checks

Strategies and quick activities

Strategies When Your Child Struggles

1. Break Apart by Place Value

Teach your child to break numbers into tens and ones. For example, 45 + 37 becomes (40 + 30) + (5 + 7) = 70 + 12 = 82.

2. Use Friendly Numbers

Adjust numbers to make them easier to work with. For 58 + 27, think 60 + 27 = 87, then subtract 2 to get 85.

3. Count Up for Subtraction

For problems like 83 - 59, start at 59 and count up: 59 + 1 = 60, 60 + 20 = 80, 80 + 3 = 83. So 1 + 20 + 3 = 24.

4. Use Compensation

For 43 - 29, think 43 - 30 = 13, then add 1 to get 14 (because you subtracted one too many).

5-Minute Practice Activities

1. Addition and Subtraction Flash Cards

Create flash cards with two-digit addition and subtraction problems. Practice for 5 minutes daily to build fluency.

2. Place Value Race

Give your child two 2-digit numbers to add or subtract. Have them solve it using place value strategies and explain their thinking.

3. Missing Number Puzzles

Create equations with missing numbers like 45 + ___ = 72 or ___ - 28 = 35 for your child to solve using place value strategies.

4. Mental Math Challenge

Call out two-digit addition and subtraction problems and have your child solve them mentally, explaining their strategy.

Check Progress

Track improvement

Mid-Year Expectations

By the middle of second grade, your child should be able to:

  • Add and subtract within 100 using place value strategies, though may still need time to work through problems
  • Break apart numbers by place value when adding (e.g., 45 + 37 as 40 + 30 and 5 + 7)
  • Use strategies like counting on or making tens for simpler problems
  • Explain their addition and subtraction strategies using place value language

End-of-Year Expectations

By the end of second grade, your child should be able to:

  • Fluently add and subtract within 100 using place value strategies
  • Solve two-digit addition and subtraction problems quickly and accurately
  • Use multiple strategies flexibly based on the numbers in the problem
  • Explain why their strategies work using place value understanding

Mastery Signs

Your child has mastered this standard when they can:

  • Add and subtract two-digit numbers quickly and accurately
  • Choose efficient strategies based on the numbers in the problem
  • Explain their thinking using place value language
  • Apply these skills to solve real-world problems
  • Check the reasonableness of their answers

Differentiation

Support for all learning levels

Below Grade Level

Practice problems focusing on addition and subtraction within 20 and adding multiples of 10, building the foundation for two-digit operations.

Download Practice Worksheet

At Grade Level

Standard practice with two-digit addition and subtraction problems using place value strategies.

Download Grade Level Worksheet

Above Grade Level

Challenging problems involving mental math with larger numbers and multi-step problems that require fluent addition and subtraction within 100.

Download Challenge Worksheet