PEMDAS, Calculators, %s, Decimals, & Zeros

P. stands for “Parentheses”… Cute story

P. stands for “Parentheses”… What do each of the following sets of ()s tell you?

P. stands for “Parentheses”… What do each of the following sets of ()s tell you? “That’s a negative sign, not an extra minus sign.” “That’s 2 times three… not 23.” I didn’t feel like typing a * sign. “I felt like intimidating you.”… the () mean nothing here! “You need to do something out of the typical EMDAS order.”

P. stands for “Parentheses”… 2 most important things to remember about parentheses? 1.) They show you where to work first! 2.) They open up a new PEMDAS! Inside every set of (), you have to start the PEMDAS order all over again!

E. stands for “Exponents”… To type an exponent, scientific calculators will offer at least one of the following options: x2x2 x3x3 yxyx ^ ONLY squares the number entered before it ONLY cubes the number entered before it Raises # entered before pushing it to power entered after pushing it.

M. & D. stand for “Multiply” & “Divide” Did you know??? Multiply does NOT ALWAYS get done before division? When you have multiplication and division (and NO parentheses telling you which one to do first), the rule is to do whatever comes first when going left to right in the problem. A. & S. stand for “Add” & “Subtract” Guess what? Addition does NOT ALWAYS get done before subtraction either! When you have addition and subtraction the rule is to go left to right as well.

So what should PEMDAS really look like?

Let’s try a few…

Calculator tips: On most calculators… if you begin typing with an operation, the LAST answer will be used. – “ANS” – To bring in a previous answer, but not at the beginning of the expression you’re typing, find the “ANS” button. (Usually you have to push 2 nd or Shift and then another button.) Negative and Minus signs are different! – Negative is usually smaller than the minus sign.

Percent to Decimal What is a fraction, really?

Percent to Decimal What is a fraction, really? – A division problem that hasn’t been finished!

Percent to Decimal What is a fraction, really? – A division problem that hasn’t been finished! Where did “percent” come from? – “_____ per cent” – “ _____ per _____” – “ _____ ___ _____”

Percent to Decimal What is a fraction, really? – A division problem that hasn’t been finished! Where did “percent” come from? – “_____ per cent” – “ _____ per _____” – “ _____ ___ _____” – So we can re-write 75% as _____ ___ _____... Or _______

Percent to Decimal 85% = 3% = 639% =.56% = Is there a pattern (“shortcut”) you see?

10’s shortcut Dividing by 10’s When you divide by tens, the decimal moves 1 place to the left for every ÷ =.023 ÷ 100 = Multiplying by 10’s When you multiply by tens, the decimal moves 1 place to the right for every x =.023 x 100 =

Decimal to Percent If we want to go the opposite direction… we need to re-write our decimal as a fraction over 100 (bc that’s what “percent” means). What do you have to do to a number if you want a new denominator, but don’t want to change the value?.89 = _.89 _ = _____ 100

Decimal to Percent.85 =.03 = 6.39 =.0056 = Is there a pattern (“shortcut”) you see?

Which ZEROS are IMPORTANT? ZEROS are only important when they affect the value of the number. Circle the zeros that are important below: What’s the rule?