I received this in my email:
Kpa nfwa jnjnbb vo Sk kizk auy phurtpijd?
Don't ignore the "mathematics" tag!
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The answer is
How many digits of Pi have you memorized?
The solution method is:
basically a Vigenere cipher where the key is given by the digits of pi: 31415926... becoming CADAEIBF... In other words, to decrypt, send each letter back in the alphabet by a number of places given by the corresponding digit of pi.
Cryptography of the day:
Happy Pi Day!
And to answer the question:
personally, I've memorised up to 3.14159265358979... (but for this puzzle we need up to 3.14159265358979323846264338327950 - up to the first zero exactly!)