Every month the price of a particular commodity falls in this order:

1024, 640, 400, 250, $\ldots$

What is the next value?
Please help me to find pattern of this sequence.


2 Answers 2


Each subsequent number is $\frac58$ of the previous one.


According to the On-line encyclopedia of integer sequences

A084912:$~~$ a(1) = 1024;$~~$ a(n) = 5*a(n-1)/8.

Puzzle: a man offered to sell me a car two years ago for \$1024; a year later his price was \$640; a little while after that he asked \$400; and last week he was willing to sell for \$250. The next time he reduces I shall buy. At what price will I buy the car if he makes consistent reductions?

Answer: a(5) = 1250/8 = \$156.25 (not an integer).

  • 1
    $\begingroup$ Stunning to find this on the OEIS. Also, my first exposure to a dumb sequence. $\endgroup$
    – Oliphaunt
    Mar 19, 2016 at 21:17

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