21 in Binary
21 in binary is 10101. Unlike the decimal number system where we use the digits 0 to 9 to represent a number, in a binary system, we use only 2 digits that are 0 and 1 (bits). We have used 5 bits to represent 21 in binary. In this article, let us learn how to convert the decimal number 21 to binary.
How to Convert 21 in Binary?
Step 1: Divide 21 by 2. Use the integer quotient obtained in this step as the dividend for the next step. Repeat the process until the quotient becomes 0.
| Dividend | Remainder |
|---|---|
| 21/2 = 10 | 1 |
| 10/2 = 5 | 0 |
| 5/2 = 2 | 1 |
| 2/2 = 1 | 0 |
| 1/2 = 0 | 1 |
Step 2: Write the remainder from bottom to top i.e. in the reverse chronological order. This will give the binary equivalent of 21.
Therefore, the binary equivalent of decimal number 21 is 10101.
☛ Decimal to Binary Calculator
Let us have a look at the value of the decimal number 21 in the different number systems.
- 21 in Binary: 21₁₀ = 10101₂
- 21 in Octal: 21₁₀ = 25₈
- 21 in Hexadecimal: 21₁₀ = 15₁₆
- 10101₂ in Decimal: 21₁₀
Problem Statements:
| What is 21 in Binary? - (Base 2) | (10101)₂ |
| What is 21 in Hexadecimal? - (Base 16) | (15)₁₆ |
| What is 21 in Octal? - (Base 8) | (25)₈ |
| Is 21 a Prime Number? | No |
| Square Root of 21 | 4.582576 |
| Cube Root of 21 | 2.758924 |
| Is 21 a Composite Number? | Yes |
| Is 21 a Perfect Square? | No |
| Is 21 a Perfect Cube? | No |
FAQs on 21 in Binary
What is 21 in Binary?
21 in binary is 10101. To find decimal to binary equivalent, divide 21 successively by 2 until the quotient becomes 0. The binary equivalent can be obtained by writing the remainder in each division step from the bottom to the top.
What is the Binary Equivalent of 21 + 3?
21 in binary number system is 10101 and 3 is 11. We can add the binary equivalent of 21 and 3 using binary addition rules [0 + 0 = 0, 0 + 1 = 1, 1 + 1 = 10 note that 1 is a carry over to the next bit]. Therefore, (10101)₂ + (11)₂ = (11000)₂ which is nothing but 24.
☛ Binary to Decimal Calculator
Find the Value of 6 × 21 in Binary Form.
We know that 21 in binary is 10101 and 6 is 110. Using the binary multiplication rules (0 × 0 = 0; 0 × 1 = 0 ; 1 × 0 = 0 and 1 × 1 = 1), we can multiply 10101 × 110 = 1111110 which is 126 in the decimal number system. [21 × 6 = 126]
How Many Bits Does 21 in Binary Have?
We can count the number of zeros and ones to see how many bits are used to represent 21 in binary i.e. 10101. Therefore, we have used 5 bits to represent 21 in binary.
How to Convert 21 to Binary Equivalent?
We can divide 21 by 2 and continue the division till we get 0. Note down the remainder in each step.
- 21 mod 2 = 1 - LSB (Least Significant Bit)
- 10 mod 2 = 0
- 5 mod 2 = 1
- 2 mod 2 = 0
- 1 mod 2 = 1 - MSB (Most Significant Bit)
Write the remainders from MSB to LSB. Therefore, the decimal number 21 in binary can be represented as 10101.
☛ Also Check:
- 248 in Binary - 11111000
- 22 in Binary - 10110
- 45 in Binary - 101101
- 3 in Binary - 11
- 223 in Binary - 11011111
- 82 in Binary - 1010010
- 24 in Binary - 11000