Plus or Minus is a puzzle to help children master the  
skills of addition and subtraction.  Numbers are
arranged in a 5 x 5 grid.  The columns add up to
the answers at the bottom, and the rows add up to
the answers on the right.  The bottom row, the
right-hand column, and the diagonal all add up to the
answer in the bottom right-hand corner, which is left
blank.  Children must place a plus or a minus sign in
front of each number to make sure everything adds up
correctly.  There are three books of sixty puzzles each.

Price: $5.95.
Private I is a game of imagination.  Children assume
secret identities and then guess who everyone is.  
They love it because it unleashes their ingenuity and
challenges their detective skills at the same time.

Because 10-sided dice are used in the game, all rolls
are strategic.  Each number on each die can be either
positive or negative, so each roll produces eight
possible moves, four forwards and four backwards.   
The children therefore get to choose which of the
questions on the game board they will ask.  Sample
questions are "Does it have an A?" "Is it soft like
babies?" and "Is it a machine?"    

The game is designed to be fun, but also to help
children with their arithmetic skills.

Price: $9.95.
Both the puzzles and the game
exist as Kindle ebooks, but neither
works well in that format
Math Books and Games