The Great Divide a Mathematical Marathon

“Bang!” goes the gun. The race is on….
Eighty racers explode from the starting gate, determined to win The Great Divide.
They surge ahead, rushing toward–OH NO!–the wide hungry mouth of a grand
canyon that claims half the racers. And this is only the beginning. More dangers
lie ahead, waiting to divide the group once, twice, three times, and more. Will
there be anyone left to cross the finish line?
“In this crafty story of a cross-country race, numerical division accounts for
the narrowing of the field. . . . All lessons should be this gratifying.” –
Publishers Weekly (starred review)