One fact about math is that the word "mathematics" comes from the Greek word "mathema" which means study, learning and science. Another fact is that if one adds ups the individual digits from the result of any number multiplied by 9, the sum of those digits is always 9.
The equals sign was invented in the 16th century by mathematician Robert Recorde because he was tired of writing "equals to." Also, the calculator was derived from the abacus. A number is divisible by 3 if the sum of its digits is divisible by 3. One more fact is that the opposite sides of a die always add up to 7.