Nezumi San

On January first, a pair of mice appeared in a house and bore six male mice and six female mice. At the end of January there are fourteen mice: seven male and seven female.

On the first of February, each of the seven pairs bore six male and six female mice, so that at the end of February there are ninety-eight mice in forty-nine pairs. From then on, each pair of mice bore six more pairs every month.

1. Find the number of mice at the end of December.
2. Assume that the length of each mouse is 4 sun. If all the mice line up, each biting the tail of the one in front, find the total length of mice

Jinkō-ki, 1715

Ruthless Thieves Stealing a Roll of Cloth

Some thieves stole a long roll of silk cloth from a warehouse. In a bush far from the warehouse, they counted the length of the cloth. If each thief gets 6 hiki, then 6 hiki is left over, but if each thief takes 7 hiki then the last thief gets no cloth at all. Find the number of thieves and the length of the cloth.

Jinkō-ki, 1643