Formulas for 7 th Grade Math Circles Ar

Formulas for 7 th Grade Math Circles A=π*r² C=πd 2 D Figures Rectangle: A=bh Square: A=s² Triangle: A= Trapezoid: A= (b + b )*h bh Regular Polygons: 2 __ 1 2 Probability: Target _____ 1 n * ( bh) 2 __ 1 2 A= Total 3 D Figures Equation Formula: y = mx + b Prisms: V=Bh Pyramids: V= Bh __ 1 3

Adding, Subtracting, Multiplying, and Dividing Rational Numbers Adding: The sign with the higher absolute value wins. Subtracting: Double negatives mean add. Multiplying/Dividing:

Finding Unit Rate: aka How much is ONE of something. To find Unit Rate, read what the question is asking. Ex. If John drives 600 miles in 6 hours, how many miles per hour did he drive?

Finding Unit Rate: Almost always $$$ ____ whatever

Simple Interest: I = prt Interest = Principal * Rate * Time How much interest will you earn if you invest $300 at an interest rate of 2% for 3 years?

Percent Change 1. Find the difference between the original and the new. 2. Divide the difference by the original. 3. Change your answer to a percent. John had $500 in his bank account. He now has $200 in his account. What is the percent change of his account?

SOLVING EQUATIONS!!! 1. Combine "Like" terms. 2. Get rid of your Constant. 3. Get rid of your Coefficient. x + 4 + x - 5 = 19 Do the opposite of what the problem is telling you to do.

SOLVING INEQUALITIES!!! 1. Combine "Like" terms. 2. Get rid of your Constant. 3. Get rid of your Coefficient. x + 4 + x - 5 > 19 Do the opposite of what the problem is telling you to do.

Graphing Inequalities Proper Point Arrow Trick

Using a Protractor Drawing Angles: 1. Put a point at your "target. " 2. Put a point at a zero. (Make note whether it is the inside zero or outside zero. ) 3. Put a point at the corresponding number.

Using a Protractor Measuring Angles: 1. Put the vertex at your "target. " 2. Put one end point at a zero. (Make note whether it is the inside zero or outside zero. ) 3. Put the other end point at the corresponding number.

Surface Area Find the area of every surface. 1. List all of your faces. 2. Find the area of every face. 3. Add them all up.

M. A. D. e a n b s o l u t e e v i a t i o n or Average Distance from the Mean

M. A. D. 1. Find the mean of the numbers. 2. Find each number's distance from the mean. 3. Find the average distance. 2, 3, 6, 10, 4, 5

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