Match Fishtank is now Fishtank Learning!

Learn More

Multi-Digit and Fraction Computation

Lesson 7


Add and subtract decimals using the standard algorithm.

Common Core Standards

Core Standards


  • 6.NS.B.3 — Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation.

Foundational Standards


  • 5.NBT.B.7

Criteria for Success


  1. Understand the role that place value plays in addition and subtraction of decimals. 
  2. Accurately use the standard algorithm to add and subtract decimals.
  3. Use addition and subtraction to solve decimal word problems.

Tips for Teachers


  • In fifth grade, students computed with decimals using all four operations and various strategies. In sixth grade, adding and subtracting with decimals is a fluency expectation. Use the problems in this lesson to review any strategies from fifth grade as needed so that students have a conceptual understanding to support the standard algorithm. Ensure students have opportunities to build towards fluency throughout the unit and the year. See our Guide to Procedural Skill and Fluency for additional information and strategies.
  • The following tools or materials are useful for this lesson: large graph or grid paper for computations, calculators to check answers.

Remote Learning Guidance

If you need to adapt or shorten this lesson for remote learning, we suggest prioritizing Anchor Problem 2 (can be done independently). Find more guidance on adapting our math curriculum for remote learning here.

Fishtank Plus

Subscribe to Fishtank Plus to unlock access to additional resources for this lesson, including:

  • Problem Set
  • Student Handout Editor
  • Google Classrom Integration
  • Vocabulary Package


Anchor Problems


Problem 1

Jayden has $20.56. He buys an apple for 79 cents and a granola bar for $1.76.

  1. How much money did Jayden spend?
  2. How much money does Jayden have now?

Guiding Questions

Create a free account or sign in to access the Guiding Questions for this Anchor Problem.


Illustrative Mathematics Jayden's Snacks

Jayden's Snacks, accessed on Sept. 28, 2017, 2:25 p.m., is licensed by Illustrative Mathematics under either the CC BY 4.0 or CC BY-NC-SA 4.0. For further information, contact Illustrative Mathematics.

Problem 2

Dan is hiking along the Pacific Coast Trail. On Sunday morning, he hikes 5.83 miles before stopping for lunch. At the end of the day, Dan has hiked a total of 12.4 miles. How many miles did he hike after lunch? 

Guiding Questions

Create a free account or sign in to access the Guiding Questions for this Anchor Problem.

Problem 3

The two problems below have been solved incorrectly. Explain the error in each problem and then correctly solve each one.

$${ 244.038+18.65 }$$ $${95.75-37.424}$$


Guiding Questions

Create a free account or sign in to access the Guiding Questions for this Anchor Problem.

Problem Set


With Fishtank Plus, you can download a complete problem set and answer key for this lesson. Download Sample

The following resources include problems and activities aligned to the objective of the lesson that can be used to create your own problem set.

  • Include fluency practice with adding and subtracting decimals.
  • Include error analysis problems of the standard algorithm applied incorrectly.

Target Task


A pitcher of water holds 48.2 ounces of water in it. The water is poured into two glasses, 12.08 ounces into one glass and 18.86 ounces into a second glass. 

  1. How much water is poured out of the pitcher?
  2. How much water is left in the pitcher?

Mastery Response


Create a free account or sign in to view Mastery Response