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National and Regional Contests
Italy Contests
ITAMO
1985 ITAMO
10
10
Part of
1985 ITAMO
Problems
(1)
A representation using floor
Source:
3/14/2006
How many of the first 1000 positive integers can be expressed in the form
⌊
2
x
⌋
+
⌊
4
x
⌋
+
⌊
6
x
⌋
+
⌊
8
x
⌋
,
\lfloor 2x \rfloor + \lfloor 4x \rfloor + \lfloor 6x \rfloor + \lfloor 8x \rfloor,
⌊
2
x
⌋
+
⌊
4
x
⌋
+
⌊
6
x
⌋
+
⌊
8
x
⌋
,
where
x
x
x
is a real number, and
⌊
z
⌋
\lfloor z \rfloor
⌊
z
⌋
denotes the greatest integer less than or equal to
z
z
z
?
floor function
calculus
integration
function