Soroban abacus and finger math

Finger Soroban 824

  Have you ever wondered why the Oriental Soroban abacus has 4 separate beads? It is in base 10, not 4 or 5, so why organize it that way? In response to yesterday’s post Hand tricks! Alexander Bogomolny linked his page explaining finger math. As I looked at that neat way of counting to 99 […]

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Hand Tricks!

Using one’s hands is practically intuitive in the math world. Counting on one’s fingers is the most basic mathematical practice one could think of. But there is other more complex math you and your kid can do with your hands! Images from Wikipedia.org For example, you are hardly limited to counting to 10. If you […]

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Who am I? A guessing game

Math Is Not Linear

“Math is not linear.” People say that, but do you believe it? Here is the history of one person’s interaction with Khan Academy. Answer this person’s riddle: WHO AM I? Judging by this historical document, how old do you think the person is? What is the grade level? Anything else you care to guess? Yes, […]

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Infinity Is Farther Than You Think

Really Big Numbers

What’s bigger, a fillion or a cometallion? These are the two big numbers my son and his friend made up one day. They couldn’t give me any more details other than “these are huge numbers” and “but smaller than a googol”. To them, all numbers went to googol, after which was the infinity. My idea […]

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