**A** **general** **formula** **by** **which** **these** **numbers** **could** **be** **derived** **was** **invented** **by** **the** **Arabian** **astronomer** **Tobit** **ben** **Korra** (836**-**901): **if** **p** = 3.2 **m** - **I**, **q**= 3.2 **m** - 1 - 1 **and** **r** = 9.2 2m - 1 - **I**, **where** **m** **is** **an** **integer** **and** **p**,**q**,**r** **prime** **numbers**, **then** 2 **m** **pq** **and** 2 **m** **r** **are** **a** **pair** **of** **amicable** **numbers**.

1007), **Rene** **Descartes**, **to** **whom** **the** **formula** **of** **Tobit** **ben** **Korra** **is** **sometimes** **ascribed**, **C**. **Rudolphus** **and** **others**.

**But** **these** **translations** **were** **regarded** **as** **imperfect**, **and** **it** **remained** **for** **Tobit** **ben** **Korra** (836**-**901) **to** **produce** **a** **satisfactory** **edition**.

**Tobit** **ben** **Korra** (836**-**901), **born** **at** **Harran** **in** **Mesopotamia**, **an** **accomplished** **linguist**, **mathematician** **and** **astronomer**, **rendered** **conspicuous** **service** **by** **his** **translations** **of** **various** **Greek** **authors**.

**These** **problems** **were** **also** **attacked** **by** **the** **Arabian** **mathematicians**; **Tobit** **ben** **Korra** (836**-**901) **is** **credited** **with** **a** **solution**, **while** **Abul** **Gud** **solved** **it** **by** **means** **of** **a** **parabola** **and** **an** **equilateral** **hyperbola**.

**By** **Tobit** **ben** **Korra** (836**-**901).

**Korra**(30s), **a** **game** **of** **skill** **for** **a** **long** **time** **in** **great** **vogue** **at** **ancient** **Greek** **drinking** **parties**, **especially** **in** **the** 4th **and** **sth** **centuries** **B**.**C**. **It** **is** **frequently** **alluded** **to** **by** **the** **classical** **writers** **of** **the** **period**, **and** **not** **seldom** **depicted** **on** **ancient** **vases**.

(**I**) **In** **the** **Korra**/30s **Si** òu43 t4 **cw** **shallow** **saucers** (4143a4a) **were** **floated** **in** **a** **basin** **or** **mixing-bowl** **filled** **with** **water**; **the** **object** **was** **to** **sink** **the** **saucers** **by** **throwing** **the** **wine** **into** **them**, **and** **the** **competitor** **who** **sank** **the** **greatest** **number** **was** **considered** **victorious**, **and** **received** **the** **prize**, **which** **consisted** **of** **cakes** **or** **sweetmeats**.

(2) **Korra**(30s **KaTaKTOs**, 1 **is** **not** **so** **easy** **to** **understand**, **although** **there** **is** **little** **doubt** **as** **to** **the** **apparatus**.