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24 Cards in this Set
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 Back
A and B are both two digit numbers. If A and B contain the same digits but in reverse order, what integer must be a factor of (A + B)?

A + B = 10 x + y + 10y + x = 11x + 11y = 11(x+y) So, 11 must be a factor of A + B.


When a question asks you about "digits", think

100h + 10t + u etc….


What is the Last Digit Shortcut? What is the units digit of 4^2 * 9^2 * 4^3?

Only pay attention to the last digit of every intermediat product. 0.


What is the Heavy Division Shortcut?

Only pay attention to first few digits…and divide.


For proper fractions between 0 and 1:As the NUMERATOR goes up, the fraction __

INCREASES


For proper fractions between 0 and 1:As the DENOMINATOR goes up, the fraction __

DECREASES


Increasing BOTH the numerator and the denominator by THE SAME VALUE brings the fraction_________

closer to 1…


When you have complex ractions, you can NEVER split the ______

DENOMINATOR


What is a Benchmark Value?

Simple fractions with which you are already familiar.


Percent change _____

Change / Original * 100.


Simple Interest equation:

Principle * Rate * Time


Compound Interest Equation:

P(1 + r/n) ^ (nt) P = Principle. R = rate. N  number of times per year. T = # of yrs


Chemical Mixture Problems: 500 ml solution is 20% alcohol. If 100 ml of water is added, what is the new concentration of alcohol?

Alcohol 100 ml 20% Alcohol 100 ml Water 400 ml 80% Water 500 ml Total 500 ml 100% Total 600 ml 100% 100 / 600 => 16.6%


1/100 => Decimal, Percent

.01, 1%


1/50 => Decimal, Percent

.02, 2%


1/25 => Decimal, Percent

.04, 4%


1/20 => Decimal, Percent

.05, 5%


1/10 => Decimal, Percent

.1, 10%


1/8 => Decimal, Percent

0.125, 12.5%


1/6 => Decimal, Percent

.1666, 16.6%


1/5 => Decimal, Percent

.2, 20%


1/4 => Decimal, Percent

0.25, 25%


The key to DS problems dealing with FDP's is to

rephrase questions / statements into equations in order to keep track of what you know and what you need to know…


DS: If a brokerage firm charged a commission of 2% of the total dollar amount of a certain trade, what was the total dollar amount of that trade? I. The dollar amount of the trade minus the brokerage firm's commission was $88,000. II. The brokerage firm's commission decreased the profit earned on the trade by 20%.

d = total dollar amount of trade. Let c  brokerage firm's commission > c = .02d Test each statement, writing equations to represent information. If the info in the statement can be combined w/ the info in the question to ield a single equationwith the single variable d, then the statement is sufficient: I.: d  c = $88,000 Rephrase: d  .02d = 88,000. Sufficient. II. P = profit before commission. p  c = .80p. We do not know p, the amount of profit before commission, so you cannot solve for c, the brokerage firm's commission. Not Sufficient.
