Editing Octal (section)

===Octal to decimal conversion===
To convert a number {{mvar|k}} to decimal, use the formula that defines its base-8 representation:
:<math>k = \sum_{i=0}^n \left( a_i\times 8^i \right)</math>

In this formula, {{math|''a''<sub>''i''</sub>}} is an individual octal digit being converted, where {{mvar|i}} is the position of the digit (counting from 0 for the right-most digit).

Example: Convert 764<sub>8</sub> to decimal:
 
:764<sub>8</sub> = 7 × 8<sup>2</sup> + 6 × 8<sup>1</sup> + 4 × 8<sup>0</sup>  = 448 + 48 + 4 = 500<sub>10</sub>

For double-digit octal numbers this method amounts to multiplying the lead digit by 8 and adding the second digit to get the total.

Example: 65<sub>8</sub> = 6 × 8 + 5 = 53<sub>10</sub>

====Method of successive duplication====
To convert octals to decimals, prefix the number with "0.". Perform the following steps for as long as digits remain on the right side of the radix: Double the value to the left side of the radix, using ''decimal'' rules, move the radix point one digit rightward, and then place the doubled value underneath the current value so that the radix points align. ''Subtract'' ''decimally'' those digits to the left of the radix and simply drop down those digits to the right, without modification.

Example:
<pre>
 0.1 1 4 6 6  octal value
  -0
 -----------
   1.1 4 6 6
  -  2
  ----------
     9.4 6 6
  -  1 8
  ----------
     7 6.6 6
  -  1 5 2
  ----------
     6 1 4.6
  -  1 2 2 8
  ----------
     4 9 1 8. decimal value
</pre>