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More decimals. Math 7. ADDING AND SUBTRACTING DECIMALS. Be sure the decimal points are lined up This will cause every other digit to fall in place Fill in any blank spaces with zeros Carry the decimal point down to where your answer will go
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More decimals Math 7
ADDING AND SUBTRACTING DECIMALS • Be sure the decimal points are lined up • This will cause every other digit to fall in place • Fill in any blank spaces with zeros • Carry the decimal point down to where your answer will go • Add or subtract like you normally would (don’t forget to “carry” or “borrow” when needed)
EXAMPLES OF ADDING DECIMALS 79.4 + 35.235 36.25 + 123.9953 14 + 9.556 Add mentally: 0.7 + 12.5 + 0.3 51.9 + 0.1 + 12 2.25 + 58 + 3.75 30.6 + 12.5 + 0.4
EXAMPLES OF SUBTRACTING DECIMALS 65.3 – 12.1 19.56 – 11.3 35.6328 – 8.519 134.55 – 104.475 220 – 147.64 3,765.08 – 1,268.582
WORD PROBLEMS A marching band has 6.5 minutes to perform at half-time. Does the band have enough time to play “America the Beautiful” and “Yankee Doodle Dandy”? If so, how much time will remain?
MOREWORDPROBLEMS How long will it take the band to play “Stars and Stripes Forever” and “The Star-Spangled Banner”?
MORE WORD PROBLEMS The Empire State Building is 443.2m tall. The Eiffel Tower is 320.8m tall. Find the difference between the heights of the two buildings. The original price of a jacket is $79.95. How much did you save if you bought the jacket on sale for $62.79?
PROPERTIES OF ADDITION Identity Property of Addition: 3.2 + 0 = 3.2 OR x + 0 = x • The Identity Property states that any number plus zero will get you back to the number you started with • 0 is called the Identity Element for addition
MORE PROPERTIES OF ADDITION Commutative Property of Addition: 3.2 + 6.7 = 6.7 + 3.2 OR x + y = y + x • The Commutative Property states that it does not matter which order you list the numbers to add them
MORE PROPERTIES OF ADDITION Associative Property of Addition: (2.5 + 6) + 4 = 2.5 + (6 + 2.4) OR(a + b) + c = a + (b + c) • The Associative Property of Addition states that if you have 3 or more numbers that are all being added together, you can add any two at a time