Home / books / Reading a binary clock

Reading a binary clock

Impress your friends by putting a binary clock on your desk. There are two types and you will learn to read both with this simple guide.

The concept of a binary clock is simple. The numbers are not displayed in base 10 (which most people are used to) but binary (base 2), so only numbers 1 and 0 are used. Since there are only two digits, lights can be used instead of digits. “On” means 1, and “Off” means 0.

Method. 1 BCD (Binary Coded Decimal) mode

1. Decode each binary digit.  The first column in each area represents the first digit (digit 10), and the second column indicates the second digit (or digit). Each column consists of 2-4 lights, each representing a power of two. Starting from the bottom, the first lamp 2 0 (1), the second 2 1 (2), the third is 2 2 (4) and the top 2 3(8). In the picture you can easily see it by the numbers on the left in each row. Add the corresponding numbers for each lit dot in the column to get the result.

2. Read off the lessons by decoding the first area. In the picture, the lower light (the first row represents 1 ) lights up in the first column, and the second column is dark ( 0 ). The combination of the digits is 10 o’clock.
NOTE: The time is displayed in 24-hour format. Subtract 12 from the number if it is greater than 13. For example, 15 would be 3 o’clock in the afternoon.

3. Determine the minutes using the same procedure as before. Again a look at the picture: In the middle area the first two (lower) lights in the first column (the second row means 2 and the first row 1, 2 + 1 = 3 ) and the first three in the second column (third Row means 4, second 2 and first 1; 4 + 2 + 1 = 7 ). By combining the two places we see that it is 37 minutes past the hour.

4. Decode the seconds. This can sometimes be difficult with a running clock because the seconds are constantly changing. In the picture, the third light in the first column (the third row stands for 4 ) and the fourth and first light in the second column (the fourth row means 8 and the first one; 8 + 1 = 9 ), and thus show 49 seconds at. If you forget what number a light stands for, look at the number on the far left of the row.

5. Combine the numbers to get the time.

Method. 2 True binary mode

1. Decode each binary digit in the same way as in BCD mode, but the two columns in each area are now treated as a single column. The lights in the right column still represent 2 0 , 2 1 , 2 2, and 2 3 ,respectively, but in the left column the pattern continues. Starting from the bottom, the first light stands for 2 4 (16) and the second for 2 5 (32). It is not necessary to go further than 2 5 , because 59 (the largest required number) is called 111011 (2 5 + 2 4 + 2 3 + 2 1 + 2 0= 32 + 16 + 8 + 2 + 1 = 59).
Remember: The clock uses lights instead of numbers; on means 1 and 0 means .

2. Read the lessons. Take the watch as an example: The last two lights in the upper row are lit (2 + 1 = 3), so it’s 3 o’clock. Note that the LEDs on the clock are arranged in rows. The lights can be arranged in columns or rows, but the reading is the same. Remember, on is 1 and off is 0. The hours on the clock can be written in binary as 0011 (3 in decimal notation).

3. Determine the minutes. Again a look at the clock: we have 011001 in the bottom row, which equals 2 4 + 2 3 + 2 0 = 16 + 8 + 1 = 25 minutes.

4. Decode the seconds in the same way as hours and minutes. The clock on the picture does not show seconds.


  • Practice creates masters! Binary watches are very hard to read off, so just practice, practice, practice!
  • Do not stay too long in mathematics. All you have to do is remember what value each bulb represents.
  • To improve your ability to memorize the combinations of lights, you can observe the seconds and count in parallel. This will make you familiar with the light combinations, and it will make reading the time easier and faster.
  • Sometimes the columns are arranged horizontally (like the clock above). However, the process of decoding time is still the same.

  • If you want to specify in front of your friends, make sure that you can read binary numbers easily. You just have to look at a regular clock to see if you’re wrong. And would not that be a pity!
What you need

  • Binary clock or wristwatch 

Check Also

Unpack APK file of an app on your Android phone

An APK file is a package file for an app that you can extract and …

Leave a Reply

Your email address will not be published. Required fields are marked *

%d bloggers like this: