![](https://blogimg.goo.ne.jp/user_image/11/9f/01fd0635300cc24848781fb30cb0d4b0.png)
[Set 2,401 on Mr. Square root]
[Japanese]
We will continue from where we ended in the last article, the actual solutions to calculate Square root using abacus. Today's example is Half-multiplication table method (Hankuku method), root is 2-digits case. We require 9 as root in the middle of calculation. Please check the Theory page for your reference. You can check the Index page of all articles.
Square root methods: Double-root method, Double-root alternative method, half-multiplication table method, half-multiplication table alternative method, multiplication-subtraction method, constant number method, etc.
Abacus steps to solve Square root of 2,401 (Answer is 49)
"1st group number" is the left most numbers in the 2-digits groups of the given number for square root calculation. Number of groups is the number of digits of the Square root.
2,401 -> (24|01) : 24 is the 1st group number. The root digits is 2.
![](https://blogimg.goo.ne.jp/user_image/3a/0a/8d6ceba82fc8bc082a3c61e23725357f.png)
Step 1: Place 2401 on CDEF.
![](https://blogimg.goo.ne.jp/user_image/59/5f/db43759643836efdc73589c8f25db082.png)
Step 2: The 1st group is 24.
![](https://blogimg.goo.ne.jp/user_image/35/ff/f0132592c3f33e1ced40f4b078acc63e.png)
Step 3: Square number ≦ 24 is 16=4^2. Place 4 on B as the 1st root.
![](https://blogimg.goo.ne.jp/user_image/0b/16/44d24ac6e390d7bee9c45f56792338d0.png)
Step 4: Subtract 4^2 from the 1st group 24. Place 24-4^2=08 on CD.
![](https://blogimg.goo.ne.jp/user_image/01/8f/a23ad7e05bdfce2c64a600b394fc99f8.png)
Step 5: Focus on 801 on DEF.
![](https://blogimg.goo.ne.jp/user_image/07/b3/df987398a688862bcdcb1e8bf1b31de1.png)
Step 6: Divide 801 by 2. Place 4005 on DEFG.
![](https://blogimg.goo.ne.jp/user_image/2f/a4/7c364b02b91e6d6623b09723a292bd39.png)
Step 7: Divide 40 on DE by the current root 4.
![](https://blogimg.goo.ne.jp/user_image/2a/bd/8ff05137af7abc6fd510c5b15ab91588.png)
Step 8: 40/4=9 remainder 4. Place 9 on C as 2nd root.
![](https://blogimg.goo.ne.jp/user_image/30/38/1e521cae427cf954194a7c91abf1021c.png)
Step 9: Place remainder 04 on DE.
![](https://blogimg.goo.ne.jp/user_image/14/ba/52784ca7b367c548d1c343f0baaefcd5.png)
Step 10: Focus on 405 on EFG.
![](https://blogimg.goo.ne.jp/user_image/21/45/bdb5bd45d88d7730677cbb8e1b9c08a1.png)
Step 11: Subtract 2nd root^2/2 from 405 on EFG. Place 000 on EFG.
![](https://blogimg.goo.ne.jp/user_image/40/8e/3f8a70e802358c78941bc6ec8cb7f916.png)
Step 12: Square root of 2401 is 49.
![](https://blogimg.goo.ne.jp/user_image/72/22/79eea1c54fc823db1e9f68b941913967.png)
Final state: Answer 49
Abacus state transition. (Click to Zoom)
![](https://blogimg.goo.ne.jp/user_image/6b/4b/a0b27876b229ac08176252d4a1840539.png)
Next article is also about Half-multiplication table method, more difficult example.
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
Index: Square root and Cube root using Abacus
http://blog.goo.ne.jp/ktonegaw/e/f62fb31b6a3a0417ec5d33591249451b
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