This set includes the math Number Properties and Formulas I want to memorize for the GMAT. Powers and Radicals are done in Excel format.
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| 727463526 | even x even = | even | |
| 727463527 | odd x odd = | odd | |
| 727463528 | even x odd = | even | |
| 727463529 | even + even = | even | |
| 727463530 | odd + odd = | even | |
| 727463531 | even + odd = | odd | |
| 727463532 | When is a number divisible by 3? | if the sum of its can be divided evenly by 3 (216, is because 2+1+6 is divisible by 3) | |
| 727463533 | When is a number divisible by 4? | if the number formed by it's last 2 digits is divisible by 4 (3,028 is because 28 is divisible by 4) | |
| 727463534 | When is a number divisible by 6? | if it is divisible by both 2 and 3 (318 is because it is even and the sum of 3+1+8 is divisible by 3) | |
| 727463535 | 0/1 = | 0 (any fraction with 0 on top is 0) | |
| 727463536 | 4/0 = | Undefined | |
| 727463537 | =7^3 | 343 | |
| 727463538 | Pythagorean Triples (lengths)? | 3:4:5 -- 5:12:13 -- 7:24:25 | |
| 727463539 | Right Isosceles triangle (lengths)? | Side, Side, Side^2 | |
| 727463540 | 30:60:90 Right Triangle (Lenghts) | x:x^(1/3):2x | |
| 727463541 | Area of a triangle? | (b*h)/2 | |
| 727463542 | Area of a circle? | pr^2 | |
| 727463543 | Circumference of a circle? | 2pr | |
| 727463544 | Equation for a line? | y=mx+b where b is the y-intercept (the point which crosses the y-axis) m is the slope of the line, and x & y are the coordinates of some point on that line | |
| 727463545 | How do you find the slope of a line? | Difference in the y-coordinates over the difference in the x coodinates | |
| 727463546 | Area of a parallelogram? | Base * Height | |
| 727463547 | Basic probability formula? | number of outcomes you want/total number of possible outcomes | |
| 727463548 | Probability that A and B will both happen? | A*B (Multiply both probabilities) | |
| 727463549 | Probability that A or B will happen? | A+B (Add both probabilities) | |
| 727463550 | Odds that something doesn't happen? | Won't = 1 - Will | |
| 727463551 | Odds that at least one thing will happen? | Will = 1 - Won't | |
| 727463552 | Problem that asks you to choose a # of items to fill specific spots, when each spot is filled from a different source? | Multiply the # of choices for each of the spots | |
| 727463553 | Permutations: single source, order matters | Multiply the # of choices for each of the spots--but the number of choices keeps getting smaller | |
| 727463554 | Permutations: single source, order matters BUT only for a selection | Multiply the # of choices for each of the spots--but the number of choices keeps getting smaller, stop when all the places are taken | |
| 727463555 | Combinations: single source, order doesn't matter | Start with the number of permutations, that is the numerator(top). The Denominator is the number of combinations (eg 4*3*2*1) | |
| 727463556 | How do you tell if it's a permutation or combination? | Permutations ask for "arraingements" Combinations ask for "Groups" | |
| 727463557 | What is the difference between a permutation or a combination? | Combinations don't care about the order of the problems | |
| 727463558 | Order of operations | PEMDAS (parenthesis, Exponents, Multiplication, Division, Addition, Subtraction) | |
| 727463559 | Adding or subtracting fractions with the same denominator | Add or subtract the numbers on top and keep the same denominator | |
| 727463560 | Adding or subtracting fractions with different denominators | Multiply both fractions to get a common denominator add or subtract as usual | |
| 727463561 | Multiplying Fractions | Multiply the numerators and put the product over the product of the denominators | |
| 727463562 | Dividing Fractions | Invert (reciprocal) the second fraction and multiply | |
| 727463563 | Adding and Subtracting Decimals | Line up the decimal points and proceed as usual | |
| 727463564 | multiplying decimals | ignor decimal points and multiply the two numbers, then count the digits to the right of the decimal points in the original numbers and place the decimal so there are the same number of digits to the right of the decimal | |
| 727463565 | Dividing Decimals | Move the decimal to the right on both numbers until there is nothing to the right of the decimal | |
| 727463566 | Key to percent increase/decrease | amount of increase/original amount = x/100 (Then cross multiply to find x) | |
| 727463567 | Exponents - Multiplying numbers with same base | add their exponents (6^2 *6^3 = 6^5) | |
| 727463568 | When is a number divisible by 3? | if the sum of its can be divided evenly by 3 (216, is because 2+1+6 is divisible by 3) | |
| 727463569 | When is a number divisible by 4? | if the number formed by it's last 2 digits is divisible by 4 (3,028 is because 28 is divisible by 4) | |
| 727463570 | When is a number divisible by 6? | if it is divisible by both 2 and 3 (318 is because it is even and the sum of 3+1+8 is divisible by 3) | |
| 727463571 | 0/1 = | 0 (any fraction with 0 on top is 0) | |
| 727463572 | 4/0 = | Undefined | |
| 727463573 | Exponents - Dividing numbers with same base | subtract the bottom exponents from the top exponents (3^6 / 3^2 = 3^4) | |
| 727463574 | Exponents - Raising a power to a power | Multiply the exponents (4^3)^2 = 4^(3*2) = 4^6 | |
| 727463575 | Distributing Exponents | When several #s are inside parenthesis, the exponent outside the parentheses must be distributed to all the #s within (4y)^2 = ((4)^2)((y)^2) = (4^2) * (y^2) = 16y^2 | |
| 727463576 | Does x^2 + x^3 = x^5? | NO | |
| 727463577 | Does x^6 - x^2 = x^4? | NO | |
| 727463578 | Does (x^2 + y^2 + z^2)/(x^2 + y^2) = z^2? | NO | |
| 727463579 | If you raise a positive fraction that is less than 1 to a power, what happens to the fraction? | It gets smaller | |
| 727463580 | If you raise a negative number to an odd power, what happens to the number? | It gets smaller | |
| 727463581 | If you raise a negative number to an even power, what happens to the number? | It becomes positive | |
| 727463582 | Any number to the first power is? | itself | |
| 727463583 | Any number to the 0 power is? | one (1) | |
| 727463584 | Any number to the negative power (y) is equal to? | The reciprocal of the same number to the positive power (y). (eg 3^-2 = 1/(3^2) = 1/9) | |
| 727463585 | Another way to write cube root 5 | 5^(1/3) | |
| 727463586 | how do you find the range of a set of numbers? | subtract the smallest number from the greatest number | |
| 727463587 | How do you find the median of a set of numbers? | arrainge #s from least to greatest and take the middle number or the average of the two middle #s | |
| 727463588 | How do you find the mode of a set of numbers? | Pick the # that occurs most frequently | |
| 727463589 | Rules for "Plugging in" for cosmic problems | 1)Pick numbers that make sense for the variable in the problem 2)Find an answer using those numbers to get the "target answer" 3)plug your #s into the answer choices to see which choice equals the target answer | |
| 727463590 | Rules for "Plugging in" the answer choices | 1)Start with choice "c" plug that into the problem to see if it works 2)If "c" is to small go larger 3) if "c" is too big try smaller 4)If you don't know try them all | |
| 727463591 | The solvability rule | You must have at least as many distinct equations as you have variables | |
| 727463592 | What happens if you multiply or divide both sides of an inequality by a negative number? | The direction of the inequality symbol changes | |
| 727463593 | How do you unfactor a quadratic equation? (x+2)(x+5) | FOIL X^2+7x+10 | |
| 727463594 | Unfactor (x+y)^2 | x^2+2xy+y^2 | |
| 727463595 | Factor x^2+2xy+y^2 | (x+y)^2 | |
| 727463596 | Unfactor (x+y)(x-y) | x^2-y^2 | |
| 727463597 | Factor x^2-y^2 | (x+y)(x-y) | |
| 727463598 | Unfactor (x-y)^2 | x^2-2xy+y^2 | |
| 727463599 | Factor x^2-2xy+y^2 | (x-y)^2 | |
| 727463600 | Distance Formula? | Rate * Time = Distance (Hint: Draw a chart) | |
| 727463601 | Work Problems? | simmilar to distance but ... Think how much of the job can be done in one hour (as a fration of the whole). | |
| 727463602 | Two fractions that equal each other with one variable how do you solve for x? | Cross multiply |
