Study Tips (Math)

To quickly see if any number is divisible by 3, add up all the digits. I the sum of the digits is evenly divisible by 3, then the whole number is. The trick works with 9 also. If the sum of the digits is evenly divisible by 9, then original number is as well.

Look at the last two digits to tell if a number is evenly divisible by 4. If 4 goes into that number evenly, ir will also go into the whole number.

To quickly multiply 9 times any single digit number, hold out ten fingers. Starting with the left-most finger, count to the number you are multiplying 9 by, and close the finger you land on. The number of standing fingers to the left is the first digit and the number to the right is the second digit of the answer.

Here's a poem that can help you remember the value of  π up to the 20th digit. Count the letters of each word to get the digits. (3.14159...)

   Sir, I send a rhyme excelling

   In sacred truth and rigid spelling  

   Numerical sprites elucidate

   For me the lexicon's dull weight.

Here's a poem that can help you interpret temperatures in Celsius:

  When it's   0 it's FREEZING,

  When it's 10 it's NOT.

  When it's 20 it's WARM,

  When it's 30 it's HOT!