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Number and Operations in Base 10: Mentally Add and Subtract CCSS 2.NBT.8 Worksheets & Activities

mentally add 10 or 100 to a given number 100–900 and mentally subtract 10 or 100 from a given number 100–900

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When mentally adding and subtracting 10s and 100s, remember that you are only working on a specific place value.

See the fact file below for more information on adding and subtracting mentally or alternatively, you can download our 27-page Number and Number and Operations in Base 10: Mentally Add and Subtract worksheet pack to utilise within the classroom or home environment.

Key Facts & Information

Learning Objective

At the end of the lesson, the student will be able to mentally add 10 or 100 to a given number 100–900 and mentally subtract 10 or 100 from a given number 100–900.

A Note for the Teacher

When mentally adding and subtracting 10 or 100, take note of the following:

  • Adding means having a greater value, and subtracting means having a smaller value
  • Dealing mentally with 10 means only computing in the tens place
  • Dealing mentally with 100 means only computing in the hundreds place
  • Remind to check the numbers in their respective place values before computing

Theory

When mentally adding and subtracting 10s and 100s, remember that you are only working on a specific place value.

  • When we add or subtract 10, it is only the tens column that changes.
    • Consider 53 + 10:
      Add only the values in the tens place.
      50+10 = 60
      The answer is 63
    • Consider 67 – 10:
      Subtract only the values in the tens place.
      60-10 = 50
      The answer is 57
  • When we add or subtract 100, it is only the hundreds column that changes.
    • Consider 124 + 100:
      Add only the values in the hundreds place.
      100+100 = 200
      The answer is 224
    • Consider 835 – 100:
      Subtract only the values in the hundreds place.
      800-100 = 700
      The answer is 735

Number and Operations in Base 10: Mentally Add and Subtract Worksheets

This is a fantastic bundle that includes everything you need to know about Number and Operations in Base 10: Mentally Add and Subtract 27in-depth pages. These are ready-to-use worksheets that align with the Common Core code 2.NBT.8 for Mentally Add and Subtract.

Complete List of Included Worksheets

  • A lesson plan
  • Warm-up activity
  • Math theory explained
  • Assisted learning activities
  • Independent learning activities
  • Extension activities and games
  • Answer keys

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Link will appear as Number and Operations in Base 10: Mentally Add and Subtract CCSS 2.NBT.8 Worksheets & Activities: https://kidskonnect.com - KidsKonnect, September 5, 2021

Use With Any Curriculum

These worksheets have been specifically designed for use with any international curriculum. You can use these worksheets as-is, or edit them using Google Slides to make them more specific to your own student ability levels and curriculum standards.