Elements of a square root and calculation step by step
Calculate by hand $\sqrt{471.969}$
We group the digits two by two and $47.19.69$ is obtained in the radicand. We look for a number that, when squared, gives $47$. The closest number is $6$ because $6\cdot6 = 36$.
| 47.19.69 | 6 |
| 6·6=36 |
This result is subtracted from $47$ and the following digits $(19)$ are moved down. We also separate the last number.
| 47.19.69 | 6 |
| -36 | 6·6=36 |
| 111.9 |
Then write the double of $6$, which is $12$. We divide $111$ by $12$, to obtain the number that it is necessary to add and to multiply. In this case it is $8$.
It is subtracted and the following group of two digits are moved down and the last digit is separated.
| 47.19.69 | 68 |
| -36 | 6·6=36 |
| 111.9 | 6·2=12 |
| -1024 | 128·8=1024 |
| 956.9 |
We repeat the previous step.
The double of $68$ is written below, $136$. Divide $956$ by $136$, to obtain the number that it is necessary to add and to multiply. In this case it is $7$, which must be added to the first line.
Operating the remainder is zero, therefore, the first line is taken and that number is the root.
| 47.19.69 | 687 |
| -36 | 6·6=36 |
| 111.9 | 6·2=12 |
| -1024 | 128·8=1024 |
| 956.9 | 68·2=136 |
| -9569 | 1367·7=9569 |
| 0 |
$$\sqrt{471969}=687$$