# Convert Decimal 21 to Octal

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

(21)10 in octal is equal to:
2110 = 258

Hence,
the octal equivalent of decimal number (21)10 is (25)8

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

For decimal values other than 21, use this below tool:

## How-to: What is (21)10 in octal?

The below step-by-step solution shows how to convert the decimal number 21 to its equivalent octal number. Representing each remainders of 21 MOD-8 operation in octal equivalents and arranging them from MSB to LSB produces the octal equivalent of 21.

Solved Example:
What is the octal equivalent of 21?

step 1 Observe the input parameters, values and what to be found:

Input values:
Decimal Number = (21)10

What to be found:
What is the octal equivalent of the decimal number (21)10?
(21)10 = (?)8

step 2 Perform successive 21 MOD-8 operation until the quotient becomes 0, and mark the first remainder as LSB and the final remainder as MSB as like the below:

Successive MOD-8 Operation for 21
 21 MOD-8 21 / 8 = 2 Remainder is 5 → LSB 2 MOD-8 2 / 8 = 0 Remainder is 2 → MSB

step 3 Arrange or write the remainders of 21 MOD-8 operation from MSB to LSB produces the equivalent octal number for decimal 21:
= 25
(21)10 = (25)8

Therefore,
the octal equivalent of decimal 21 is (25)8. 