Pocket Books, 1977. Likely an early printing of this edition, possibly a first. Pocket Books didn't include a number line until 1979, so this copy was printed sometime in 1977 or 1978.
Good. Rubbing and shelf wear to covers with discoloration to back cover, likely transposed from another book it was shelved next to. Tape across spine at top and bottom edge, but with no apparent tears or reason for the application visible. Binding is very strong, spine is straight and all pages are clean and unmarked, though tanned.