Last Updated：2025/11/23
(mathematics, number theory) A number equal to the number of dots in a geometric figure formed of dots. The series begins with unity and is formed so that subtracting each from the following, and treating the series so formed in the same way, by a continuation of the process, yields equal differences.
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figurate number
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Source Word
figurate number
Noun
(mathematics,
number
theory)
A
number
equal
to
the
number
of
dots
in
a
geometric
figure
formed
of
dots.
The
series
begins
with
unity
and
is
formed
so
that
subtracting
each
from
the
following,
and
treating
the
series
so
formed
in
the
same
way,
by
a
continuation
of
the
process,
yields
equal
differences.
Japanese Meaning
図形数：点を用いて構成された幾何学的図形内の点の数と対応する数。系列は1から始まり、連続する項の差を取ると一定の差（等差数列）が得られるように形成される数学的な数を指す。
Sense（1）
(mathematics,
number
theory)
A
number
equal
to
the
number
of
dots
in
a
geometric
figure
formed
of
dots.
The
series
begins
with
unity
and
is
formed
so
that
subtracting
each
from
the
following,
and
treating
the
series
so
formed
in
the
same
way,
by
a
continuation
of
the
process,
yields
equal
differences.
（ plural ）
