Mon Prof Augmenté
Reading a Binary Switch Panel
A row of four switches stands for a binary number, where each switch is worth double the one to its right. A switch that is on adds its value to the total, and a switch that is off contributes nothing, so 1011 works out to 8 + 2 + 1 = 11.
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Age 18: open this week
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In the picture
- The glowing bulb above the first switch: it marks a 1 in that column, so that column’s value is counted.
- The lever of the second switch, pointing down: it marks a 0, so the 4 belonging to that column stays out of the total.
- The engraved plate reading 8: place values double from right to left, giving 1, 2, 4, 8.
- The pencilled slip reading 11: the sum 8 + 2 + 1 is the decimal value of the binary number 1011.
Examples
- A colour channel in a photo editor runs from 0 to 255 because eight binary places add up to 255 at most.
- File permissions written as 755 come from three bits each, where read, write and execute are worth 4, 2 and 1.
Key takeaways
- Each binary place is a power of two, doubling as you move left: 1, 2, 4, 8, 16.
- The decimal value is the sum of the place values whose digit is 1.
Carry on in the app
Three questions on this lesson. It has left the free week, so its quiz is for subscribers.
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