Determine the probability that for a base ten positive integer x chosen at random from 1 to 9999 inclusively, this relationship is satisfied:
(sod(x))2 = x+2, where sod(n) denotes the sum of the digits in the base ten representation of n.
denCt = 0
Do
ix = InStr(l$, ",")
If ix Then
denCt = denCt + 1: l$ = Mid(l$, ix + 1)
Else
denCt = denCt + 1
End If
Loop Until ix = 0
ReDim den(denCt)
l$ = txtDenom.Text
denCt = 0
Do
ix = InStr(l$, ",")
If ix Then
denCt = denCt + 1: den(denCt) = Val(Left(l$, ix - 1))
l$ = Mid(l$, ix + 1)
Else
denCt = denCt + 1: den(denCt) = Val(l$)
End If
Loop Until ix = 0
finds
2
23
62
119
194
287
398
7 7.000700070007001D-04 1428.428571428571
That is the list of 7 integers satisfying the relationship, and the probability of 0.00070007..., or 1/1428.428571428571....
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Posted by Charlie
on 2011-01-26 15:37:33 |
solution using QuickBasic
