Which of the following three numbers, in decimal, octal and hexadecimal notation respectively, is or are equivalent to the binary number (11011001)?

1.in decimal

2.in octal

3.(D9) in hexadecimal

A1 only

B2 only

C1 & 2 only

D1 & 3 only ✓ Correct

Correct answer: (D) 1 & 3 only

Explanation

The binary number 11011001 equals 217 in decimal, so the first value matches.

Statement 1 is correct because 128 plus 64 plus 16 plus 8 plus 1 gives 217.

Statement 2 is wrong because grouping the bits in threes gives octal 331, not 661.

Statement 3 is correct because grouping the bits in fours gives hexadecimal D9.

Octal groups binary digits in threes and hexadecimal groups them in fours.

Hexadecimal D stands for the decimal value 13.

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