Stacking Changes · Deep Dive 5

Finn reads this

Each percent change is one multiplication. When there are several, do them in order, each one on the result of the last.

The used car

Finn reads this

A used car starts at $10,000. The dealer adds $259 for cleaning and shipping: $10,259. Then a 25 percent markup: 10,259 times 1.25 is $12,823.75. Then 10 percent more for the salesperson's commission: 12,823.75 times 1.10 is $14,106.13, rounded to the cent.

$10,000 + $259 = $10,259$10,259 × 1.25 = $12,823.75$12,823.75 × 1.10 = $14,106.125 ≈ $14,106.13

Notice the fee is a dollar amount, so it is added, not multiplied. The markup and the commission are percents, so each one is a multiplier, applied to whatever the total was just before it.

ElleMath-speak

Successive percent changes can be applied by multiplying by each multiplier in order.

FinnPlain English

Each change is one multiplication. Do them in order.

Two changes in a row

Finn reads this

A $50 game gets a 20 percent markup, then goes on sale for 10 percent off. Markup: 50 times 1.20 is $60. Discount, on the $60: 60 times 0.90 is $54. Two multipliers, in order.

$50 × 1.20 = $60$60 × 0.90 = $54

Let me try a few

NC standards: NC.7.RP.3, NC.7.EE.3.

Where to go next

Let me try a few5 problems on stacking Changes. Next: Tile 3, The SurpriseUp 10 percent, then down 10 percent All tilesAll 3 parts of this lesson. Tell us what you thought about this tileA few quick questions about just this tile. It takes a few minutes, and opens in a new tab so you keep your place.