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Adding and Subtracting Whole Numbers. Section 1.2. Objectives. Find the sum of two or more whole numbers Find the difference of two whole numbers Estimate the sum or difference of whole numbers Find the perimeter of a polygon. Objective 1: Find the sum of two or more whole numbers.
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Adding and Subtracting Whole Numbers Section 1.2
Objectives • Find the sum of two or more whole numbers • Find the difference of two whole numbers • Estimate the sum or difference of whole numbers • Find the perimeter of a polygon
Objective 1 • Addends are numbers that are added • Sum is the result of adding • To add whole numbers • Write numbers in columns so place values are lined up • Add each column, starting with the ones (or units) column • If sum of column is greater than 9, write the ones digit and carry the tens digit to next column
Objective 2 • To subtract whole numbers • Write numbers in a column so place values are lined up • Subtract in each column, starting with one (or units) column • When numbers in a column can’t be subtracted, borrow 1 from next column and rename by adding 10 to upper digit, then subtract • When exercise is worded “Subtract A from B,” you must reverse the order: B – A.
Objective 3 • Estimate by rounding numbers to a specified place and add or subtract
Objective 4 • Polygon is a closed figure whose sides are line segments • Perimeter of a polygon is the distance around the outside • To find perimeter, add the lengths of the sides
Getting Ready for Algebra • Objective: Solve an equation of the form x + a = b, or x – a = b, where a, b, and x are whole numbers
Getting Ready for Algebra • Equation - statement about numbers that say two expressions are equal • Variables or Unknowns – letters that represent numbers • Solution – numbers that make equations true • Addition and subtraction are inverse operations
Getting Ready for Algebra • To solve an equation using addition or subtraction • Add the same number to each side of the equation to isolate variable, or • Subtract the same number to each side of the equation to isolate variable • Check the solution by substituting it for the variable in the original equation