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Published byDenis Wilkinson Modified over 9 years ago
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Adding and Subtracting Rules
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When adding or subtracting numbers that have the same sign, you add the numbers together and keep the sign. 3 + 5 = 8 7 + 15 = 22 - 2 – 12 = - 14 - 15 – 16 = - 31
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When adding or subtracting numbers that have opposite signs, you subtract the numbers and keep the sign of the larger number -5 + 10 = 5 12 – 7 = 5 -15 + 3 = - 12 – 2 + 9 = 7
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Associative Laws The "Associative Laws" say that it doesn't matter how we group the numbers (i.e. which we calculate first)...when we add (a+ b) + c = a + (b + c)
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Distributive Law The "Distributive Law" is the BEST one of all, but needs careful attention Try the calculations yourself: 3 × (2 + 4) = 3 × 6 = 18 3×2 + 3×4 = 6 + 12 = 18 Either way gets the same answer
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Commutative Laws The "Commutative Laws" say we can swap numbers over and still get the same answer... a + b = b + a
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Inverse Operation The operation that reverses the effect of another operation. Example: Addition and subtraction are inverse operations Another Example: Multiplication and division are inverse operations.
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