Using this mathematical trick you can figure out the day of the week for any date
H. Armstrong Roberts/ClassicStock/Alamy
Time has cycles and we use a cyclic number system to deal with time. What time is 5 hours after 10pm? I would appreciate it if you could say 3am instead of 15pm. I know that 10 + 5 is not 3, but I also know that when it reaches 12 it resets to zero. In mathematical terminology, this is called modular arithmetic. That is, divide 15 by 12 and keep the remainder. We write this as 10 + 5 = 3 modulo 12.
Modulo arithmetic has many uses, from cryptography to magic tricks. There is…
Source: www.newscientist.com
