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LessonsCatch the Flaw

Lesson 05 · Maths · Decimal division

Step 1 of 4

Find the wrong step

Glowing wire being shared among seven star-shaped badge displays
Your lessonDecimal divisionCore

The Star-Badge Supply Drop

Mission control shares 18.9 metres of glowing core wire equally among seven badge displays. Each display also needs 0.35 metre of border wire.

Core wire
18.9 m shared equally
Displays
7
Border per display
0.35 m

Your question

How much total wire does each display receive?

Lumi’s answer: “Each display needs 27.35 metres of wire.”

1

Step 1 of 4

Find the wrong step

Find where the reasoning first breaks

Start with Step 1 and move downward. Choose the first line that stops making sense.

Later lines may be wrong too. Pick the first mistake.

Lumi’s work

These lines form one solution. Read them from top to bottom.

  1. 1

    Find one share of the core wire: 18.9 ÷ 7.

  2. 2

    Because 189 ÷ 7 = 27, write 18.9 ÷ 7 = 27.

  3. 3

    Add the border: 27 + 0.35 = 27.35.

  4. 4

    Each display needs 27.35 metres.