# Chinese remainder theorem facts for kids

The **Chinese remainder theorem** is a theorem from number theory. It is about congruence. The original form was:

*How many soldiers are there in Han Xin's army? – If you let them parade in rows of 3 soldiers, two soldiers will be left. If you let them parade in rows of 5, 3 will be left, and in rows of 7, 2 will be left.*

The theorem says that many times there will be a solution to this question.

The Chinese remainder theorem is used in cryptography, for example for the RSA algorithm.

The theorem was first discovered in the 3rd century AD by the Chinese mathematician Sunzi in *Sunzi Suanjing*.

## See also

In Spanish: Teorema chino del resto para niños

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Chinese remainder theorem Facts for Kids. *Kiddle Encyclopedia.*