|
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 + 5b
- E. 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.
Other Strategy
Sessions:
