Estimation on the SAT

Why the SAT Emphasizes Estimation

Estimation is a smart test day strategy when exact computation is unnecessary. If the answer choices are far apart, a good estimate can get you to the right option faster than a full calculation.

This lesson shows how to round numbers strategically and keep track of whether your estimate is a little high or a little low. The goal is to stay accurate enough to distinguish among the answer choices.

A Simple Definition Unlocks Estimation

Round to friendly numbers that keep the arithmetic simple, but do not round so aggressively that you lose the structure of the problem. You can round one number up and another down to keep the estimate balanced.

Always compare your estimate to the original problem to make sure it is in the right ballpark. If the options are close together, estimation may not be safe, so switch to exact computation.

Work Through Estimation Step by Step

Estimate $49 \\times 21$ by rounding and then compare to the exact product.

Use Desmos to Check Estimation

Desmos is not necessary for estimation, but it can confirm your approximate range if you want to be safe.

Use Desmos only if you are unsure. Estimation is meant to save time.

Estimation is usually faster without Desmos because the goal is quick mental math. Desmos can be useful only as a quick check if you are unsure.

Expert move: Estimate first; use Desmos only to confirm the range after you choose an estimate. Estimation is meant to save time.

• Desmos features used: quick calculation.
• Common mistake: rounding in opposite directions and losing accuracy.

Practice Estimation with SAT-Style Questions

Estimate to choose the best answer.

Key Takeaways to Remember for Estimation

• Round to friendly numbers and track whether you rounded up or down.
• Use estimation when choices are far apart.
• Desmos can confirm if you need a quick check.