Professor Layton and the Diabolical Box

Puzzle 119: The Fake Coins

Original diagram for Puzzle 119: The Fake Coins

One of five bags holds lighter fake coins, so how few weighings on a 200-unit scale find it?

Chapter
Chapter 4
Location
Watchtower 1st Floor
Picarats
30 picarats
Type
Tap Answer
Region
Same in all versions
Hint 1: A gentle nudge. Tap to flip.
Hint 1

You don't have to weigh whole bags.

Tap to flip back
Hint 2: The key idea. Unlocks after the previous card is flipped.
Hint 2

Take a different number of coins from each bag.

Tap to flip back
Hint 3: Almost there. Unlocks after the previous card is flipped.
Hint 3

How far below the expected weight the total falls tells you which bag is fake.

Tap to flip back
Answer: See the answer. Unlocks after the previous card is flipped.
Answer

The answer is 1 weighing.

Tap to flip back
Solution, FAQ and sources

Solution

Take 1 coin from bag 1, 2 from bag 2, and so on up to 5 from bag 5: 15 coins in all. If they were all real they'd weigh 150 units, which is within the scale's limit.

Each fake coin is 1 unit light, so the total comes up short by exactly the number of the fake bag. For example, 147 units means bag 3. One weighing is enough: **1**.

About this puzzle

Five numbered bags each hold 10 coins. One bag is all fakes, which weigh 9 units instead of 10. Your scale shows weights up to 200 units. What’s the fewest weighings needed to find the fake bag?

Unofficial fan guide, not affiliated with LEVEL-5 or Nintendo. Puzzle description, hints and solution written by Hint by Hint.

Similar puzzles: Puzzle 120: Tug of War, Puzzle 074: PU!, Puzzle 072: Scrambled Photos, Puzzle 113: A Stack of Dice

All Professor Layton and the Diabolical Box puzzles

FAQ

What is the answer to Puzzle 119, The Fake Coins, in Professor Layton and the Diabolical Box?

The answer is 1 weighing.

Where do you find Puzzle 119 in Diabolical Box?

Puzzle 119 appears in Chapter 4, in the Watchtower 1st Floor area.

How many picarats is Diabolical Box Puzzle 119 worth?

30 picarats.

Sources

Facts checked on November 14, 2026

Unofficial fan guide. Not affiliated with, endorsed by, or sponsored by LEVEL-5 Inc. Professor Layton, The New World of Steam, and all related names, characters, and trademarks are the property of their respective owners.