FDPs

Things one must know:

• Common FDP equivalents (MGMAT FDPs p66)
• Prefer fractions for doing multiplication or division, but prefer decimals and percents for doing addition or subtraction, for estimating numbers or for comparing numbers.
• FDPs and word translations (MGMAT FDPs p68) - X percent is (X/100)
  
  Advanced:
• Repeating decimals: Generally, just do the long division to determine the repeating cycle. However, if the denominator is 9, 99, 999 or another power of 10 minus 1, then the numerator gives you the repeating digits (perhaps with leading zeroes).
• Terminating decimals: When written as a fraction and if, after being fully reduced, the denominator has any prime factors besides 2 or 5, then its decimal will not terminate. If the denominator only has factors of 2 and/or 5, then the decimal will terminate.
• Unknown digits problems:
  1) Look at the answer choices first, to limit your search.
  2) Use other given constraints to rule out additional possibilities.
  3) Focus on the units digit in the product of sum.
  4) Test the remaining answer choices.
• When you work with formulas that act on decimals, avoid shortcuts and follow directions precisely.
• Fractions and Exponents & Roots: The effect of raising a fraction to a power varies depending upon the fraction's value, sign and the exponent. Be ready to generate outcomes with test numbers such as 1/2 or 3/2. Not that taking the square root of a proper fraction raises its value toward 1.
• Use a mixture chart for weighted average problems that involve percents and percent change. You can also use the formula, and leave the percents (keeping the % sign) when you solve.
• You can plug a value that is a fraction, a ratio, a decimal or a percent straight into percent change equations as long as you keep the labels straight.
• Estimating decimal equivalents:
  1) Make the denominator the nearest factor of 100 or another power of 10.
  2) Change the numerator or denominator to make the fraction simplify easily.
  3) Small percent adjustment, increase/decrease the result by the same percent you increased/decreased the nominator/ denominator.
  Try not to change both the numerator and denominator, especially in opposite directions.