Plugging In — The Universal Shortcut

When a problem uses variables and the answers are expressions, pick a number and test.

Method:

1. Pick easy numbers (2, 3, 5 — avoid 0 and 1)

2. Solve the problem with your chosen numbers

3. Plug the same numbers into each answer choice

4. The choice that matches is correct

Example: "If x items cost d dollars, how much do 5 items cost?"

Pick x = 2, d = 10. Each item costs $5. Five items cost $25.

Plug into choices. 5d/x = 5(10)/2 = 25. That's the answer.

When to use: Abstract problems, variables in answers, "in terms of" questions, messy algebra.

Caution: If two choices give the same result, pick different numbers and retest only those two.

Reference:

Wikipedia: SAT

https://en.wikipedia.org/wiki/SAT