2.19

## Weizmann Institute of Science

Skip to 0 minutes and 0 secondsSo, time for the solution. I asked you before - I gave you a hint saying that the third row here, which looks like some kind of binary, is equal to the Roman numeral row above. In the Roman numeral row above, we have a house with 7 in it is equal to 142,857 and this is equal to something with a house in it! Well, we already know that that something is a 7 so we can equate this 7 with 0100. Now, this is not binary because 100 in binary is 4, but it is binary reflected Gray code. So this is binary reflected Gray code, and once you remember that we can do the rest.

Skip to 0 minutes and 46 secondsThis is equal to - 1111 - in binary reflected Gray code - is 10. 0101 is 6, so we have 10 to the power of 6, minus 0001 which is just 1, and all this divided by 7. Now, 10 to the power of 6 minus 1 is 999999 That's strange! Is 999,999 divided by 7, equal to the 7 in the house, which means it's equal to - 142,857. Is it? Get out your calculators and check! It is! How strange!

# The solution to the computer symbology part of course challenge

Great! - We’re well on our way now. Have you ever wondered whether you can literally ‘read’ barcodes. Go on! Mark this step as complete and click ‘next’ and we’ll learn how to do that in the next activity.