pre-algebra 2.8 adding decimals
Post on 18-Dec-2014
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Review of last week:
Review of last week:
Review of last week:
= + - -5 - 8
-9 - 10
= + - -6 - - 10
-3 - - 15
Review of last week:
Pre-Algebra
Unit 2 Lesson 8 & 9
Adding Decimals
Part 1 & 2
What do you know about adding decimals?
Think-Pair-Share
What is a decimal?A point or dot used to separate the whole number part from the fractional part of a number.
Rules:
Same sign (+ +, - -)
add numbers together, keep sign
Different signs (+ - , - +)
find difference, take sign of higher number
Examples:
1) 2.8 + 14.5
2) -3.3 + 14.2
3) -9.17 + (-4.27)
4) 10.8 + -4.5
Same/Diff. Problem
Activity:
SMOTDYour decimal: Your Birthday! month.day
Example: August 11 = 8.11
Example: January 6 = 1.06
+ +
- -
+ -
- +
Activity:
1)
1)
1)
1)
Comparing expressions
Comparing expressions
Inverse operations and decimals
y + 33.2 = 12.5
y - - 23.7 = 48.1
Inverse operations and decimals
x + 14.5 = 39.4 x - 19.2 = 8.3
x - (- 6.6) = 7.7 x - (-10.3) = - 4.5
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