As I have said, it was a number code.

以前说过，这是数字暗码。

It seemed to be a number code, where groups of numbers replace letters.

看起来用的是数字密码，用一组组数字代表字母。

Then there's code number 3, PVC, which is made of a polymer called " polyvinyl chloride" .

然后是代码 3，聚氯乙烯。它是由一种叫聚氯乙烯的聚合物组成的。

Every item found on the archaeological dig is given a code number.

【code】考古发掘时发现的每一件物品都给了编号。

First, he translated mathematical statements and equations into code numbers so that a complex mathematical idea could be expressed in a single number.

首先，他将数学陈述和方程式翻译成代码数字，这样复杂的数学思想就可以用一个数字来表达。