Arithmetic on the GRE — Harder Than You Think

GRE Quantitative · Axiom Academy

It's harder than you think — not because the numbers are big, but because they're hiding a rule "I'm good at arithmetic" is not the same as "I'm good at GRE arithmetic" The GRE doesn't test whether you can multiply . It tests whether you can think strategically about numbers — because a huge share of its arithmetic questions are built so the obvious first instinct is wrong. Basic computation is the baseline, not the skill being tested. Problems that look simple but hide a structural trick Questions that test whether you understand a rule, not whether you can compute Comparison questions where the "obviously bigger" quantity isn't Multi-step problems where one small misstep ruins the whole answer Watch a value go up 20%, then down 20%. Intuition says it should land right back where it started. Watch where it actually settles. A 20% increase followed by a 20% decrease lands at 96 — a net change of −4%, not 0%. That's the whole unit in miniature: the arithmetic is easy, the rule is the part that's tested. The gap isn't a fluke of 20% — try any percent Drag the slider to change the percent. The bar always goes up by , then down by of the new value. Watch the net-change readout — it never returns to 0%, and the gap gets bigger as r grows, not smaller. The net change is always (as a fraction of 100) — a straight algebra fact: (1+r)(1-r) = 1 - r^2 . That's why the GRE loves this question shape. 2^ 10 vs. 4^5 — which is bigger?

This is the written version of the interactive lesson above. See the full GRE Quantitative course.