
Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion 
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March 24th, 2017, 05:35 AM  #11 
Senior Member Joined: May 2016 From: USA Posts: 1,047 Thanks: 430 
$a,\ b \in \mathbb N^+\ and\ a + b = 10 \implies (10t + a)(10t + b) =$ $100t^2 + 10t(a + b) + ab = 100t^2 + 100t + ab = 100 * t(t + 1) + ab \implies$ $(10t + 5)^2 = 100 * t(t + 1) + 25.$ One general rule and a specific consequence. Not limited in theory to two and three digit numbers. 

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2digit, methods, numbers, squaring 
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