(And adults, of course!) These math puzzles test your brain and critical-thinking skills and provide some constructive, educational fun. Math riddles and puzzles come in plenty of different varieties.

Unlike Roman, Maya or Iñupiaq numerals, this isn’t a total reimagining of numbers. Instead, it’s an uncanny parallel universe. Any number without zeros retains its old appearance (1,776 is still 1,776 ...