perplexus.info :: Numbers : A rare event

A rare event (Posted on 2010-07-03)

This year (by June 2010) IT already happened thrice and will occur one more time, on October 1st.

Next time SAME THING will occur on two different dates in 2011 and on 6 different dates in 2012.

In 2013 - only during one day and then in the following years IT will present itself at least once a year till 2036.

In 2037 - not even once.

What is IT (a.k.a. SAME THING )?
If IT = f(YEAR) what is f(2020)?
In what year in this century f(YEAR) is maximal?

No Solution Yet Submitted by Ady TZIDON

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What IT is (parts 1 and 2) (spoiler)

| Comment 1 of 3

1) day * month = last two digits of year

In 2010, happens on 1/10/10, 2/5/10, 5/2/10, and 10/1/10

2) f(2020) = 5 (IT happens in months 1,2,4,5,10)

3) f(2060) = 7 (IT happens in months 2,3,4,5,6,10,12),

which might be maximal. Don't have time to check.

Posted by Steve Herman on 2010-07-03 15:04:08

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