https://en.wikipedia.org/wiki/Archimedes%27s_cattle_problem wrote:
<<Archimedes's cattle problem (or the problema bovinum or problema Archimedis) is a problem in Diophantine analysis, the study of polynomial equations with integer solutions. Attributed to Archimedes, the problem involves computing the number of cattle in a herd of the sun god from a given set of restrictions. The problem was discovered by Gotthold Ephraim Lessing in a Greek manuscript containing a poem of forty-four lines, in the Herzog August Library in Wolfenbüttel, Germany in 1773.

The problem, from an abridgement of the German translations published by Georg Nesselmann in 1842, and by Krumbiegel in 1880, states:

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* Compute, O friend, the number of the cattle of the sun which once grazed upon the plains of Sicily, divided according to color into four herds, one milk-white, one black, one dappled and one yellow. The number of bulls is greater than the number of cows, and the relations between them are as follows:*
*White bulls = ( 1/2 + 1/3 ) black bulls + yellow bulls,*

Black bulls = ( 1/4 + 1/5 ) dappled bulls + yellow bulls,

Dappled bulls = ( 1/6 + 1/7 ) white bulls + yellow bulls,

White cows = ( 1/3 + 1/4 ) black herd,

Black cows = ( 1/4 + 1/5 ) dappled herd,

Dappled cows = ( 1/5 + 1/6 ) yellow herd,

Yellow cows = ( 1/6 + 1/7 ) white herd.

If thou canst give, O friend, the number of each kind of bulls and cows, thou art no novice in numbers, yet can not be regarded as of high skill. Consider, however, the following additional relations between the bulls of the sun:
*White bulls + black bulls = a square number,*

Dappled bulls + yellow bulls = a triangular number.

If thou hast computed these also, O friend, and found the total number of cattle,

then exult as a conqueror, for thou hast proved thyself most skilled in numbers.

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The problem remained unsolved for a number of years, due partly to the difficulty of computing the huge numbers involved in the solution. The general solution was found in 1880 by Carl Ernst August Amthor (1845–1916), headmaster of the Gymnasium zum Heiligen Kreuz (Gymnasium of the Holy Cross) in Dresden, Germany. Using logarithmic tables, he calculated the first digits of the smallest solution,

showing that it is about 7.76 × 10^{206544} cattle,

far more than could fit in the observable universe.>>