Loving exploration of numbers and basic concepts. Starts with symbols and origins, tally marks and grouping, then moves through other operations. Chapters on mechanical aids (abacus, soroban, odometers and calculators) are particularly interesting. Nice illustrations!

Would be an excellent reader for latter elementary school; focuses more on concepts of arithmetic than rote practice. Italicized "problems" are scattered through the text, providing more examples of the concept at hand. Later chapters gloss over commutative and associative aspects, eventually using them to examine negative numbers. This felt a bit rushed, and didn't go far enough into the inverse of multiplication (as one example).