An old woman goes to market and a horse steps on her basket and crushes the eggs. The rider offers to pay for the damages and asks her how many eggs she had brought. She does not remember the exact number, but when she had taken them out two at a time, there was one egg left. The same happened when she picked them out three, four, five, and six at a time, but when she took them seven at a time they came out even. What is the smallest number of eggs she could have had?
Oystein Ore mentions a puzzle with a dramatic element from Brahma-Sphuta-Siddhanta (Brahma’s Correct System) by Brahmagupta (born 598 AD) https://www-math.ucdenver.edu/~wcherowi/courses/m5410/crt.pdf