[Set 421,875 on Mr. Cube root]Zoom
[Japanese]
We start the actual solutions to calculate Cube root using abacus. The calculation becomes more complicated but interesting.
Today's example is simple - basic Triple-root method, root is 2-digits case and 1st root is greater than or equal to 4.. Please check the Theory page for your reference.
Cube root methods: Triple-root method, constant number method, 3a^2 method, 1/3-division method, 1/3-multiplication table method, 1/3-multiplication table alternative method, Multiplication-Subtraction method, 3-root^2 method, Mixing method, Exceed number method, Omission Method, etc.
Abacus steps to solve Square root of 421,875
(Answer is 75)
"1st group number" is the left most numbers in the 3-digits groups of the given number for cube root calculation. Number of groups is the number of digits of the Cube root.
421,875 -> (421|875) : 421 is the 1st group number. The root digits is 2.
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Step 1: Set 421875. First group is 421.
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Step 2: Cube number smaller than 421 is 343=7^3. Place 7 on D as 1st root.
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Step 3: Place 421-343=078 on GHI. (-a^3)
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Step 4: Place Triple root 3x7=21 on AB.
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Step 5: Repeat division by 21 until 4th digits next to 1st root. (/3a)
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Step 6: 78/21=3 remainder 15. Place 3 on F and 15 on HI.
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Step 7: Divide 158 by 21.
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Step 8: 158/21=7 remainder 11. Place 7 on G and 011 on HIJ.
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Step 9: Divide 117 by 21.
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Step 10: 117/21=5 remainder 12 Place 5 on H and 012 on IJK.
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Step 11: Divide 37 by current root (1st root) 7. (/a)
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Step 12: Ansewer is 5 and place 5 on E as 2nd root.
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Step 13: Place 37-1st root x Answer=37-7x5=02 on FG. (-ab)
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Step 14: Focus on 25 on GH.
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Step 15: Place 25-2nd root^2=25-5^2=00 on GH. (-b^2)
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Step 16: Focus on 125 on JKL.
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Step 17: Place 125-2nd root^2=125-5^3=000 on JKL. (-b^3)
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Step 18: Cube root is 75.
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Final state: Answer 75
Abacus state transition. (Click to Zoom)
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Next article is also about Cube root calculation (Triple-root method).
Related articles:
How to solve Cube root of 1729.03 using abacus? (Feynman v.s. Abacus man)
http://blog.goo.ne.jp/ktonegaw/e/cff5d6e7ecaa07230b9cc7af10b23aed
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[Japanese]
We start the actual solutions to calculate Cube root using abacus. The calculation becomes more complicated but interesting.
Today's example is simple - basic Triple-root method, root is 2-digits case and 1st root is greater than or equal to 4.. Please check the Theory page for your reference.
Cube root methods: Triple-root method, constant number method, 3a^2 method, 1/3-division method, 1/3-multiplication table method, 1/3-multiplication table alternative method, Multiplication-Subtraction method, 3-root^2 method, Mixing method, Exceed number method, Omission Method, etc.
Abacus steps to solve Square root of 421,875
(Answer is 75)
"1st group number" is the left most numbers in the 3-digits groups of the given number for cube root calculation. Number of groups is the number of digits of the Cube root.
421,875 -> (421|875) : 421 is the 1st group number. The root digits is 2.
Step 1: Set 421875. First group is 421.
Step 2: Cube number smaller than 421 is 343=7^3. Place 7 on D as 1st root.
Step 3: Place 421-343=078 on GHI. (-a^3)
Step 4: Place Triple root 3x7=21 on AB.
Step 5: Repeat division by 21 until 4th digits next to 1st root. (/3a)
Step 6: 78/21=3 remainder 15. Place 3 on F and 15 on HI.
Step 7: Divide 158 by 21.
Step 8: 158/21=7 remainder 11. Place 7 on G and 011 on HIJ.
Step 9: Divide 117 by 21.
Step 10: 117/21=5 remainder 12 Place 5 on H and 012 on IJK.
Step 11: Divide 37 by current root (1st root) 7. (/a)
Step 12: Ansewer is 5 and place 5 on E as 2nd root.
Step 13: Place 37-1st root x Answer=37-7x5=02 on FG. (-ab)
Step 14: Focus on 25 on GH.
Step 15: Place 25-2nd root^2=25-5^2=00 on GH. (-b^2)
Step 16: Focus on 125 on JKL.
Step 17: Place 125-2nd root^2=125-5^3=000 on JKL. (-b^3)
Step 18: Cube root is 75.
Final state: Answer 75
Abacus state transition. (Click to Zoom)
Next article is also about Cube root calculation (Triple-root method).
Related articles:
How to solve Cube root of 1729.03 using abacus? (Feynman v.s. Abacus man)
http://blog.goo.ne.jp/ktonegaw/e/cff5d6e7ecaa07230b9cc7af10b23aed
Please place your mouse on the buttons and click one by one. These are blog ranking sites.
