# Convert (21)8 into Decimal Equivalent

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

(21)8 in decimal is equal to:
218 = 1710
0o21 = 1710
Hence,
the decimal equivalent of octal number (21)8 is (17)10.

where,
218 is the given octal number,
8 in 218 represents the base-8 or octal number system,
17 is the decimal equivalent of octal number 21,
10 in 1710 represents the base-10 or decimal number system.

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

1. The right most digit in the given base-8 number 21 is a Least Significant Digit (LSD).
2. The left most digit in the given base-8 number 21 is a Most Significant Digit (MSD).
3. The LSD of 21 should be multiplied with 80.
4. The MSD of 21 should be multiplied with 8(no. of digits - 1).
5. For octal values other than 21, use this below tool:

## How-to: What is (21)8 in decimal?

The below step-by-step solution shows how to convert (21)8 into decimal equivalent. To find the decimal equivalent of (21)8, multiply 80 with the right most digit, 81 with the left subsequent digit and so on until the left most digit of the given octal number 21. The sum of all individual products is the decimal equivalent of octal 21.
Solved Example:
Convert (21)8 into decimal equivalent.
step 1 Observe the input parameters, values and what to be found.

Input values:
Octal Number = 218

What to be found:
What is the decimal equivalent of (21)8?

step 2 Multiply 80 with the right most digit, 81 with the left subsequent digit and so on until the left most digit of the given octal number 21. Therefore, arrange the given decimal number 21 in the expression form as like the below:
= (2 x 81) + (1 x 80)

step 3 Resolve the powers of 8 in the above equation:
= (2 x 8) + (1 x 1)

step 3 Simplify the above equation further:
= 16 + 1
= 17
(21)2 = (17)10

Therefore,
17 is the decimal equivalent of octal number (21)8 