What is Binary?
Binary is a system of counting. You’re most likely familiar with counting using 0–9, that’s called the decimal number system. Binary is an alternative number system that existed before computers were invented. When computer scientists started building computers, they selected binary as the counting system that would run the computer’s brain. Binary is simple, it’s just 0 or 1. All a computer’s decision-making comes down to YES or NO, TRUE or FALSE, 1 or 0.
But if computers only think in 1 and 0, do they understand numbers like 3, 20, or 500? Yes! Binary numbers only use the 0 and 1 characters, but they can represent any number we can think of. We just have to learn how to translate a decimal number to a binary number.
Value of Binary Digits
Each binary number is made up of digits, each with its own value. Each digit can either be 1 or 0. If a digit is 1, it’s ON. If it’s 0, it’s OFF. To get the final number, add together the values of the ON digits. Below we can see the value of the first 5 binary digits.
Place values for the first 5 binary digits, 1, 2, 4, 8, 16
To translate 18 to binary we write 10010. We turn ON the 5th digit (value 16) and the 2nd digit (value 2).
18 in binary, 10010 (16 + 2)
Binary Examples
The number 3 in binary is written 11. We turn ON the first and second digit. The value of the first digit is 1 and the value of the second digit is 2. Together they equal 3.
3 in binary, 11 (1 + 2)
The number 5 in binary is written 101. We turn ON the first and third digit. The value of the first digit is 1 and the value of the third digit is 4. Together they equal 5.
5 in binary, 101 (1 + 4)
The number 20 in binary is written 10100. We turn ON the fifth and third digit. The value of the fifth digit is 16 and the value of the third digit is 4. Together they equal 20.
20 in binary, 10100 (16 + 4)
Continue Learning
Related resourceActivity: Binary BotComplete a simple exercise using only binary numbers!
