Up 25%, down 25% is not a wash: the SAT math trap

Short answer: The second percent hits a new, bigger base. Multiply the factors; never cancel them.

The trap, in one question

Tempting answer: $100  (+25 − 25 = 0)

Correct answer: $93.75  (100 × 1.25 × 0.75)

How to spot it in 3 seconds

The second percent hits a new, bigger base. Multiply the factors; never cancel them.

FAQ

What is the up 25%, down 25% is not a wash trap on the SAT?

Example: A $100 stock rises 25%, then falls 25%. What is the new price? The tempting answer is $100 (+25 − 25 = 0); the correct answer is $93.75 (100 × 1.25 × 0.75).

How do you avoid the up 25%, down 25% is not a wash trap?

The second percent hits a new, bigger base. Multiply the factors; never cancel them.

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