Subcategories

• Day 1

  Algebra Tricks

  Module 4 Day 1 Challenge Part 1

  Module 4 Day 1 Challenge Part 2

  Module 4 Day 1 Challenge Part 3

  Module 4 Day 1 Challenge Part 4

  Module 4 Day 1 Your Turn Part 1

  Module 4 Day 1 Your Turn Part 2

  Module 4 Day 1 Your Turn Part 3

  Module 4 Day 1 Your Turn Part 4
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  Ah, ok. I signed up for MOAA and AMC 8 and I'm trying to go through as many modules as I can, so some days I'll be doing something and some days I'll be doing the other.

• Day 2

  Number Algebra

  Module 4 Day 2 Challenge Part 1

  Module 4 Day 2 Challenge Part 2

  Module 4 Day 2 Challenge Part 3

  Module 4 Day 2 Your Turn Part 1

  Module 4 Day 2 Your Turn Part 2

  Module 4 Day 2 Your Turn Part 3

  Module 4 Day 2 Your Turn Part 4
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  18
  Posts

  

  Great question! The trick really only works as long as

  The units digits of the two numbers sum to 10, and The rest of the numbers, apart from their units digits, are the same.

  ... like you could try writing 62 and 64 as 60+2 and 60+4, but when you multiply them the terms won't add and cancel nicely like they did in Prof. Loh's explanation.

  I hope that made sense to you; if it didn't I'd be happy to clarify.

  This trick is slightly related to Difference of Squares, but also very different. It does not actually currently have a name... so I guess you could call it Prof. Loh's Trick.

• Day 3

  Simplifying Expressions

  Module 4 Day 3 Challenge Part 1

  Module 4 Day 3 Challenge Part 2

  Module 4 Day 3 Challenge Part 3

  Module 4 Day 3 Challenge Part 4

  Module 4 Day 3 Your Turn Part 1

  Module 4 Day 3 Your Turn Part 2

  Module 4 Day 3 Your Turn Part 3
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  7
  Posts

  

  @smartlion I've been told by our website host that this issue has been fixed now. Thank you for your help with this, and sorry for the trouble!

• Day 4

  Finding the Unknown

  Module 4 Day 4 Challenge Part 1

  Module 4 Day 4 Challenge Part 2

  Module 4 Day 4 Your Turn Part 1

  Module 4 Day 4 Your Turn Part 2

  Module 4 Day 4 Your Turn Part 3

  Module 4 Day 4 Your Turn Part 4
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