21 in Octal

Decimal 21 in octal conversion provides the detailed information on what is the octal equivalent of (21)10, and the step-by-step work for how to convert the decimal (base-10) number 21 to its octal (base-8) equivalent.

(21)10 in octal is equal to:
(21)10 = (?)8

Perform successive MOD-8 operation for decimal 21, and mark the initial remainder as LSB and the final remainder as MSB as like the below.

MOD-8 of 21	21 / 8 = 2	Remainder is 5 → LSB
MOD-8 of 2	2 / 8 = 0	Remainder is 2 → MSB

Arrange the remainders from MSB to LSB forms the octal equivalent of 21.
21₁₀ = 25₈

Hence,
21 in octal is 25

where,
21₁₀ is the given decimal number,
10 in 21₁₀ represents the base-10 or decimal number system,
25₈ is the octal equivalent of the decimal 21,
8 in 25₈ represents the base-8 or octal number system.

Important Notes: (21)10 in Octal
The below are some of the important notes to be remembered while converting the (base-10) decimal number 21 into a (base-8) octal equivalent.

1. The first remainder of MOD-8 of 21 is a Least Significant Bit (LSB).
2. The final remainder of MOD-8 of 21 is a Most Significant Bit (MSB).
3. The remainders of MOD-8 of 21 should be written from MSB to LSB to form the octal equivalent for the given decimal number (21)10.