Newly Added July 2008:

Mr. Base Ten Invents Mathematics by Bethany H. Tucker. Very simple story-based math.

Upper elem: How to Count Like a Martian by Glory St. John - Systems of counting including the Egyptian base ten, the Babylonian base sixty, the Hindu system using three symbols, and the abacus and computer systems. Out of print.

Upper elem: Counting Systems, The Familiar and the Unusual, by Marnie Luce. Lots of practice with number bases in this one. Out of print.

Listed Prior:

12 Ways to Get to 11 by Eve Merriam

Hello Math Readers The 512 Ants on Sullivan Street (L. 4) by Carol A. Losi (sequence is Base 2 / binary)/ Ready or Not, Here I Come! (L. 2) Counting to 100 by 1s, 2s, 5s, 10s and 20's;  Monster Math Picnic Grace Maccarone, L. 1

The King's Chessboard z Birch, David/Grebu  1988  Doubling exponentially. Based on historical tale

Mouse Count by Ellen Stoll Walsh, more than just a counting book, combos of 10 as the number of mice in the jar increases, the mice out of the jar decrease

One Hundred Hungry Ants  z  Pinczes, Elinor J. 1993 Division, factors, very clever early intro

One Hundred Is A Family by Pat Munoz Ryan - Combinations that make 10, counting up by 10s to make 100.

Senefer: A Young Genius in Old Egypt z by Beatrice Lumpkin - wonderful living book on several accounts, but as Senefer learns the Egyptian way of writing numbers, it emphasizes how number bases are constructed. Addition and multiplication are woven in the story as well.

Ten by Vladimir Radunsky - illustrations are a bit bizarre,but it IS a book about 10

Ten Friends by Bruce Goldstone - various ways to combine numbers to amount to 10, nice book

Young Math  Base Five    Adler, David/Ross, Larry   1975   Number base systems

Counting Systems   Luce, Marnie/Stenson, Charles  1969   History & description of number systems