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Table of Contents
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 100β900 and mentally subtract 10 or 100 from a given number 100β900.
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
- Consider 53 + 10:
- 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
- Consider 124 + 100:
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.Β 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.