英语中具有明确词根的单词+各种衍生词汇上万个，通过词根词缀和构词法来记忆单词，可以将看起来风马牛不相及的词汇联系起来，增加记忆，大大提高你的学习效率。

上期我们讲解了"Number Words"中常见的“从一到五”的词根，本期我们继续来看生活中常见的“数字词根”

词根"dec"在拉丁语和希腊语中均表示"ten".

A decade lasts for ten years; the decimal system is based on ten; and a decahedron is a geometrical shape with ten sides.

December n.十二月；是以你为罗马历中一年为10个月，December曾经就是10月，后来改历为1年12个月，在前面增加了2个月，December便成了12月。Octber 曾经是“八月”，这也符合词根"Oct"所表示的“8”，同样的原因，现在成了10月。

词根"cent"源于拉丁语中的"centum",表示"one hundred"

一句话解释“分”的概念
A dollar is made up of a hundred cents, though other monetray systems use centavos or centimes as the smallest coin.

一句话说明“世纪”与“蜈蚣”
A centipede has what appears to be a hundred feet, though the actual number varies greatly. But there really are a hundred years in a century.

词根"mill"表示"a thousand", "a thousandth".

一句话看懂关于“千”的度量衡。
A millennium is a thousand years, and a million is a thousand thousands. But a milligram is a thousandth of a gram, a milliliter is a thousandth of a liter, and a millimeter is a thousandth of a meter.

词根"hemi-"源于希腊语，"semi-"源于拉丁语，表示"mean".

hemisphere = hemi半+sphere球体=n. 半球
semicircle = semi半+circle圆周=n. 半圆

此外，法语中也同样有源于拉丁语的前缀"demi-",也表示half. 英文中的法语词demitasse 表示小杯咖啡（half the size of a regular cup）