The octal equivalent of the binary number 1011101011 is

2017

The octal equivalent of the binary number 1011101011 is

  1. A.

    7353

  2. B.

    1353

  3. C.

    5651

  4. D.

    565

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Correct answer: B

Concept: Binary uses base 2 and octal uses base 8, and 8 = 2³. So exactly three binary bits encode one octal digit (values 0 to 7). To convert binary to octal, partition the bits into groups of three starting from the rightmost (least significant) bit, padding the leftmost group with leading zeros, then replace each 3-bit group by the octal digit it represents.

Application: The 10-bit number 1011101011 is grouped from the right and the top group is padded to three bits:

  1. Group from the right into threes: 1 | 011 | 101 | 011.

  2. Pad the leftmost group with leading zeros: 001 | 011 | 101 | 011.

  3. Convert 001 = 0·4 + 0·2 + 1·1 = 1.

  4. Convert 011 = 0·4 + 1·2 + 1·1 = 3.

  5. Convert 101 = 1·4 + 0·2 + 1·1 = 5.

  6. Convert 011 = 0·4 + 1·2 + 1·1 = 3.

  7. Read the octal digits in order: 1, 3, 5, 3, giving 1353.

Cross-check: Convert through decimal as an independent route. 1011101011 in binary equals 512 + 128 + 64 + 32 + 8 + 2 + 1 = 747 in decimal. Dividing 747 by 8 repeatedly gives remainders 3, 5, 3, 1 (read upward) = 1353 in octal, which matches.

Therefore the octal equivalent is 1353.

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