If a composite number by multiplying any number make some number, the product will be solid.
如果一个合数乘以任意数得到某个数，那么该乘积是一个立体数。
合数 A 与数 B 相乘得 C。D 为 A 的因子，E 记 D 量 A 的次数，故 A = D·E。因 A 乘 B = C 且 A = D·E，所以 C = D·E·B，即三数之积，故 C 为立体数。
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For let the composite number A by multiplying any number B make C; I say that C is solid. For, since A is composite, it will be measured by some number.
设合数A乘以任意数B得C，则C是立体数。
[VII. Def. 13] Let it be measured by D; and, as many times as D measures A, so many units let there be in E.
因为A是合数，所以它被某个数D量尽（VII.定义13）。
Since then D measures A according to the units in E, therefore E by multiplying D has made A.
设D量尽A的次数为E，则E乘以D得A（VII.定义15）。
[VII. Def. 15] And, since A by multiplying B has made C, and A is the product of D, E, therefore the product of D, E by multiplying B has made C.
由于A乘以B得C，且A是D、E之积，故D、E之积乘以B得C，因此C是立体数。