Adding and Subtracting Decimals

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Objective

I can add and subtract decimals using the standard algorithm.

Part 1 of 4

Warm-up video

Math with Mr. J · 9:06Vetted channel

We don't generate video — this one is by Math with Mr. J on YouTube. The practice questions and exit ticket below were drafted by AI for this objective, and every question is editable in the teacher guide.

Part 2 of 4

Key concepts

3 concepts

  1. 1

    When adding or subtracting decimals, the first step is to line up the decimals to ensure that all the places are lined up correctly.

  2. 2

    When adding or subtracting decimals, you can use placeholder zeros to the right of a decimal without changing its value, which helps to line up the numbers.

  3. 3

    When subtracting decimals, remember to borrow if the top digit is smaller than the bottom digit; do not simply drop the bottom number.

Part 3 of 4

Practice

12 questions

1

What is the most important step to remember when adding or subtracting decimals?

2

Why is it acceptable to add placeholder zeros to the right of a decimal when adding or subtracting?

Part 4 of 4

Exit ticket

Quick comprehension check

Solve: 35.75 + 18.9 using the standard algorithm. Show your work, lining up the decimals correctly.

Sample answer included in the free materials

Get the materials

Teacher guide, student handout, and slides — free, in Google Docs format

  • Teacher Guide

    Complete lesson plan with answer keys and alternate activities

  • Student Handout

    Printable worksheet

  • Slides

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