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Module 5
Addition and Subtraction of Numbers to
1000 with Word Problems to 100



Throughout this module, students will: 
  • add and subtract within 1000.
  • understand that when adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, and ones and ones. 
  • understand that sometimes when adding or subtracting it is necessary to compose or decompose tens or hundreds. 
  • mentally add and subtract 10 or 100 to a number (ex. 456 +10, 721-100) 
  • explain why addition and subtraction strategies work, using place value and the properties of operations. 
Terminology Definition Illustration
Algorithm A step-by-step procedure to solve a particular
type of problem.
+ 57

Compensation  A strategy that involves adjusting one number to a tens number and then adjusting the other number to keep a balance. 
Compose To make 1 larger unit from 10 smaller ones. (ex.  1 ten for 10 ones) 
Decompose To break 1 larger unit into 10 smaller units.  (ex. 10 tens from 1 hundred) 
Also referred to as "unbundling" or "borrowing". 
New Groups Below A strategy to show newly composed units on the line below the addition algorithm (can be shown working left to right or right to left) 
Simplifying Strategy  A strategy to make mental addition or subtraction easier.  299+7 could be thought of as 299+1 +6=300+6=306
Chip Model A pictorial strategy using place value to solve addition or subtraction. 
Associative Property of Addition Changing the grouping of 3 or more addends does not change the sum
Additional Resources: 

compensation subtraction from JD K-4 Math on Vimeo.



Dr. Peter Smith, Superintendent

P.O. Box 606
DeWitt, NY 13214

Phone: (315) 445-8300

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