已知数

yī gè yǐ zhī shù shì mǒu shù duì shù de shù

一个已知数是某数对数的数。

A known number is the logarithm of another number.

rú guǒ xiǎng qiú chū wèi zhī shù nǐ shǒu xiān děi zhī dào yǐ zhī shù

如果想求出未知数，你首先得知道已知数。

If you want to get the unknown number, you should know the known number first.