Problem
Solving
Topic: Problem Solving
Strategy Used: Picking Numbers
Picking numbers is a powerful alternative to solving
problems by brute force. Rather than trying to work
with unknown variables, you can pick concrete values
for the variables. Any answer choice that does not work
for the concrete values cannot be the correct answer.
Pick simple numbers to stand in for the variables.
Next, try all the answer choices, ditching those that
don't agree with the question information. Remember
to keep the values you've picked for the variables constant
throughout the problem. If more than one answer choice
works, try different values. The correct choice must
work for all possible numbers.
Consider the following
example:
If a and b are odd integers,
which of the following is an even integer?
A. a(b - 2)
B. ab + 4
C. (a + 2)(b - 4)
D. 3a + 5bE.
a(a + 6)
You can run through the answer choices quite quickly
by using the picking numbers strategy. Try a = 3, b
= 5. Only (D), 9 + 25 = 34, is even.
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