g4c2

=Grade 4 Math, Chapter 2=


 * Vocabulary**

__**Commutative property of addition:**__ Numbers can be added in any order and the sum will be the same.

__**breaking apart:**__ Mental math method used to rewrite numbers as the sum of numbers to form an easier expression.

__**Associative property of addition:**__ The grouping of addends can be changed and the sum will be the same.

__**compensation:**__ Adding and subtracting the same number to make the sum or the difference easier to find.

__**Identity property of addition:**__ The sum of any number and zero is that number.

__**addends:**__ The numbers that are added together to find a sum.

__**sum:**__ The result of adding numbers together.

__**difference:**__ The answer when subtracting two numbers.

__**rounding:**__ Replacing a number with a number that tells about how many or how much.

__**front-end estimation:**__ A way to estimate a sum by adding the first digit of each addend and adjusting the result based on the remaining digits.

__**overestimate:**__ An estimate that is greater than the exact answer.

__**underestimate:**__ An estimate that is less than the exact answer.


 * __inverse operations__:** Two operations that undo each other. Addition and subtraction are inverse operations. Multiplication and division are inverse.

__**variable:**__ A symbol or letter that stands for a number.

__**number expression:**__ A symbol or letter that stands for a number.

__**equation:**__ A number sentence that uses the equal sign (=) to show that two expressions have the same value.

__**solution:**__ The value of the variable that makes an equation true.

__**solve**__: Find a solution to an equation.

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