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Problem Solving With Percentages
3 Types of Problems with %'s:
How to Solve:
Essential Vocab:
☆ "is" → = ☆ Change % into decimals
☆ "of" → x ☆ "what percent" → write decimal as a percent
☆ "what" → variable n
Percentages
☆ % = percent
☆ percent → per - cent → literally means out of 100
☆ 100 does not always = 100%
☆ can be > 100 → 1.25=125%
Integers
☆ Integers: positive and negative numbers
☆ "Chip Method":
Division W/Integers:
☆ Multiplication + Division = Inverse Operations
Multiplication W/Integers:
☆ Commutative: a x b = b x a
-Means "the opposite of" ⤵
-3 x -2 = the opposite of 3 x -2 = -6 → opposite of → = 6 → -3 x -2 = 6
🚫 -3 groupssomethinghing ⤴
Solve it this way because it is easier for students to understand ⤴
a) 2 x 5 = 2 groups of 5 = (+++++) (+++++) = 10
b) 2 x -5 = 2 groups of -5 = (-----) (-----) = -10
c) -2 x 5 = 5 x -2 = 5 groups of -2 = (--) (--) (--) (--) (--)
d) -2 x -5 = the opposite of 2 x -5 = 2 groups of -5 = (-----) (-----) = -10 → opposite = 10
Subtraction W/Integers:
🟡 = Positive and 🔴 = Negative
☆ negative +/- positive = zero pair → 🔴 🟡 = 0 → cancel eachother out
🟡🟡🟡🟡🟡 - 🟡 = 🟡🟡🟡🟡
🔴🔴🔴🔴🔴 - 🔴 = 🔴🔴🔴🔴
🟡🟡🟡🟡🟡 - 🔴 → 🟡🟡🟡🟡🟡 - 🔴 (+ 🔴 🟡) → 🟡🟡🟡🟡🟡🟡🔴 - 🔴 = 🟡🟡🟡🟡🟡🟡
🔴🔴🔴🔴🔴 + 🟡 → 🔴🔴🔴🔴🔴 + 🟡 (+ 🔴 🟡) → 🔴🔴🔴🔴🔴🔴🟡 - 🟡 = 🔴🔴🔴🔴🔴🔴
a) 3 - -1 = 4
🟡🟡🟡 - 🔴 = 🟡🟡🟡🟡
🟡🟡🟡🟡🔴 - 🔴 = 🟡🟡🟡🟡
b) -6 - -2 = -4
🔴🔴🔴🔴🔴🔴 - 🔴🔴 = 🔴🔴🔴🔴
c) 3 - -4 = 7
🟡🟡🟡 - 🔴🔴🔴🔴 = 🟡🟡🟡🟡🟡🟡🟡
🟡🟡🟡🟡🟡🟡🟡🔴🔴🔴🔴 - 🔴🔴🔴🔴 = 🟡🟡🟡🟡🟡🟡🟡
d) -2 - -3 = 1
🔴🔴 - 🔴🔴🔴 = 🟡
🔴🔴🔴🟡 - 🔴🔴🔴 = 🟡
Addition W/Integers:
🟡 = Positive and 🔴 = Negative
🟡🟡🟡🟡🟡 + 🟡 = 🟡🟡🟡🟡🟡🟡
🔴🔴🔴🔴🔴 + 🔴 = 🔴🔴🔴🔴🔴🔴
🟡🟡🟡🟡🟡 + 🔴 = 🟡🟡🟡🟡
🔴🔴🔴🔴🔴 + 🟡 = 🔴🔴🔴🔴
☆ negative +/- positive = zero pair → 🔴 🟡 = 0 → cancel eachother out
a) 3 + -2 = 1
🟡🟡🟡 + 🔴🔴 = 🟡
or 🟡🟡🟡 = 1
+ 🔴🔴
b) -6 + -2 = -8
🔴🔴🔴🔴🔴🔴 + 🔴🔴 = 🔴🔴🔴🔴🔴🔴🔴🔴
c) 3 + -4 = -1
🟡🟡🟡 + 🔴🔴🔴🔴 = 🔴
d) -2 + -1 = -3
🔴🔴 + 🔴 = 🔴🔴🔴
Decimals
☆ Base-10 system = Decimal System = 1-to-10 Relationship
☆ Decimal separates the part form the whole
☆ Decimal sits to the right of the unit
Converting
Repeating VS Terminating
☆ is not a decimal because it is not terminating or repeating - it is an irrational #
Addition:
Subtraction:
Multiplication:
Division: