← Day 9
UNIT 7 / 8 · LESSON 1 / 4 · 24 MINUTES

Anchor every percent to its base

Percent changes depend on the original amount. A 20% increase and a 20% decrease do not cancel.

01 / THE METHOD

Make it repeatable

  1. Identify the base amount.
  2. Convert the percent to a multiplier.
  3. Multiply once per change.
  4. Check whether the question asks for a new value or a difference.
02 / WORKED EXAMPLE

Watch the method in action

A $100 item rises 20%, then falls 20%.
  1. After the increase: 100 × 1.20 = 120.
  2. After the decrease: 120 × 0.80 = 96.
  3. The second percent uses 120 as its base.

The final price is $96, four dollars below the start.

03 / QUICK CHECK

Try it yourself

What is the final value?

04 / PRACTISE AND CHECK

Apply the method to real questions

Start with guided questions and feedback. Then take a fresh independent set without hints. Reach at least 80% on that set to record this lesson.

Pass the quick check above to unlock practice.