# Book:Daniel Shanks/Solved and Unsolved Problems in Number Theory

## Daniel Shanks: Solved and Unsolved Problems in Number Theory

Published $\text {1962}$.

### Subject Matter

Why is the force of gravity at double the distance reduced by a factor of $4$? Why is the factor apparently $4$ exactly, rather than $4$ approximately? Probably because we live in a space of exactly $3$ dimensions.