Estimating BIG Number Multiplication
This game is based on noughts and crosses, but can be played by 2 or 3 players. Instead of a blank 3 by 3 grid, draw up a grid of 6 by 6 squares and write into them (in a random order) the numbers: 70, 110, 130, 140, 160, 190, 210, 220, 260, 290, 300, 320, 370, 380, 420, 460, 470, 480, 530, 560, 610, 660, 680, 700, 750, 820, 830, 850, 940, 970, 1050, 1110 and 1250.