🌊 MermaidsGrade 8Reading: grades 7-9Fractions of a numberPlace valueMultiplicationWord problems
The Sunken Citadel Mystery
The Coral Vault of Aquamarina has been breached! The legendary Heart of the Reef, a giant pearl that powers the city's bioluminescent glow, is gone. The Royal Pearl Keeper was trapped in a heavy-water bubble while the thief fled. As a detective of the deep, you must analyze the ocean currents and solve the clues to unmask the rogue tide-weaver.
Suspects
Possible suspects
Cross off a row as each clue rules it out. On screen, tap a row.
21 of 21 still in play
| Name | Primary Magic | Secondary Ability | Trident Wrist Favor | Hair Color | Tactical Vulnerability |
|---|---|---|---|---|---|
| Oceanus | coral-shaping | bioluminescence | right-wrist bracelet | anemone pink | high-frequency-pitch |
| Tethys | siren-song | deep-vision | left-wrist bracelet | anemone pink | high-frequency-pitch |
| Sedna | current-riding | deep-vision | left-wrist bracelet | seafoam green | high-frequency-pitch |
| Poseidon | siren-song | pearl-mimicry | left-wrist bracelet | kelp brown | high-frequency-pitch |
| Kai | siren-song | thermal-venting | right-wrist bracelet | anemone pink | dried-salt |
| Lir | storm-summoning | deep-vision | right-wrist bracelet | anemone pink | high-frequency-pitch |
| Triton | coral-shaping | electric-touch | right-wrist bracelet | anemone pink | silver-netting |
| Jacques | hydro-kinesis | pearl-mimicry | right-wrist bracelet | anemone pink | dried-salt |
| Delphine | current-riding | electric-touch | right-wrist bracelet | anemone pink | dried-salt |
| Ursula | storm-summoning | pearl-mimicry | right-wrist bracelet | seafoam green | high-frequency-pitch |
| Sirena | storm-summoning | deep-vision | right-wrist bracelet | kelp brown | dried-salt |
| Coralia | siren-song | pearl-mimicry | right-wrist bracelet | anemone pink | dried-salt |
| Ondine | current-riding | pearl-mimicry | left-wrist bracelet | anemone pink | silver-netting |
| Marina | hydro-kinesis | pearl-mimicry | left-wrist bracelet | kelp brown | dried-salt |
| Muriel | siren-song | pearl-mimicry | left-wrist bracelet | seafoam green | high-frequency-pitch |
| Ronan | siren-song | thermal-venting | right-wrist bracelet | seafoam green | dried-salt |
| Mazu | hydro-kinesis | thermal-venting | right-wrist bracelet | kelp brown | silver-netting |
| Thallo | siren-song | electric-touch | left-wrist bracelet | seafoam green | silver-netting |
| Caspian | siren-song | electric-touch | right-wrist bracelet | anemone pink | dried-salt |
| Calypso | hydro-kinesis | bioluminescence | left-wrist bracelet | anemone pink | dried-salt |
| Nerida | hydro-kinesis | pearl-mimicry | left-wrist bracelet | seafoam green | silver-netting |
Clue 1
Fractions of a number
We intercept an encrypted message sent to the rogue tide-weavers. Only a specific fraction of the bubbly signals contain true data while the rest are decoys. Calculating the exact fraction narrows down the suspect's magic style.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
T
4
27
39
T
4
27
58
39
49
23
21
39
12
3
21
T
4
19
12
39
T
4
27
39
6
35
40
50
29
39
3
T
4
58
3
33
2/3 of 6 =T
2/3 of 9 =R
3/6 of 66 =G
1/5 of 95 =U
4/8 of 24 =S
2/10 of 115 =D
1/4 of 108 =H
5/10 of 6 =N
1/4 of 84 =O
5/10 of 116 =I
2/5 of 125 =L
4/5 of 50 =A
7/8 of 40 =M
2/8 of 196 =F
1/5 of 195 =E
2/10 of 145 =V
0/16 letters found
Clue 2
Place value
A deep-sea hydrophone records the thief's high-speed escape. By identifying the correct decimal place values in the recorded frequency, we isolate the unique wrist signature of the culprit.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
R
2000
90
600
500
8000
200
R
2000
90
900
8000
3000
R
2000
300
4000
50
80
50
8000
1000
300
R
2000
5000
90
400
600
900
9000
40
20
400
70
What is the value of the 2 in 842,346?R
What is the value of the 9 in 710,691?I
What is the value of the 6 in 72,618?G
What is the value of the 5 in 33,504?H
What is the value of the 4 in 70,347?O
What is the value of the 8 in 58,756?T
What is the value of the 3 in 247,379?A
What is the value of the 9 in 29,062?F
What is the value of the 8 in 41,285?L
What is the value of the 2 in 49,287?W
What is the value of the 9 in 74,922?S
What is the value of the 3 in 153,475?B
What is the value of the 5 in 35,196?K
What is the value of the 7 in 28,275?D
What is the value of the 1 in 901,947?M
What is the value of the 2 in 41,525?U
What is the value of the 4 in 57,491?N
What is the value of the 4 in 84,938?C
What is the value of the 5 in 32,350?E
0/19 letters found
Clue 3
Multiplication facts (1-12)
The Royal Guard counts the columns of damaged coral in the palace gardens. Multiplying the rows of ruined reefs helps us calculate the exact energy output of the thief's weakness.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
T
16
27
50
T
16
27
49
50
36
84
20
88
49
9
25
9
66
49
50
9
25
84
10
T
16
8 × 2 =T
1 × 10 =L
9 × 1 =D
11 × 8 =O
7 × 12 =A
11 × 6 =R
7 × 7 =I
10 × 2 =V
5 × 10 =E
5 × 5 =S
6 × 6 =F
9 × 3 =H
0/12 letters found
Clue 4
Word problems
A friendly sea turtle witnessed the getaway but speaks only in word puzzles about current speeds and swimming times. Resolving the turtle's math riddle reveals the exact defense we need to capture the thief.
Solve each problem to learn its letter, then write the letters in the boxes to fill in the missing word.
Astrandof hairturnedupatthescene.
A
63
91
116
61
82
91
116
19
117
91
K
There were 67 luminescent kelp. 4 were used up. How many luminescent kelp are left?A
There were 120 pearls. 3 were used up. How many pearls are left?I
Tide-hunter found 89 coral shards yesterday and 2 more today. How many coral shards in all?N
There were 136 luminescent kelp. 20 were used up. How many luminescent kelp are left?E
Tide-hunter found 2 coral shards yesterday and 59 more today. How many coral shards in all?M
There were 32 coral shards. 13 were used up. How many coral shards are left?P
There were 106 coral shards. 24 were used up. How many coral shards are left?O
0/7 letters found
Clue 5
Fractions of a number — the last clue
We recover a discarded pouch containing stolen pearls. Finding the precise fraction of these glowing gems that carry physical evidence reveals the exact hair color of the culprit.
First solve each problem. Then find each answer in the list below and cross that sentence out. One sentence will be left — that's exactly what the villain did!
Step 1 — solve these
1/8 of 32 = ?
1/5 of 45 = ?
1/3 of 30 = ?
1/2 of 4 = ?
2/4 of 22 = ?
3/6 of 16 = ?
3/8 of 32 = ?
1/3 of 3 = ?
1/2 of 10 = ?
1/4 of 28 = ?
5/10 of 12 = ?
Step 2 — cross out the sentence with each answer
1.The villain sang a distracting melody, then heated the surrounding water to a boil.
2.The villain conjured a localized whirlpool, then glowed brightly in the dark reef.
3.The villain sang a distracting melody, then disguised the pearl as a common stone.
4.The villain glided swiftly along the gulf stream, then sparked with a static charge.
5.The villain conjured a localized whirlpool, then disguised the pearl as a common stone.
6.The villain molded the solid coral gates, then glowed brightly in the dark reef.
7.The villain conjured a localized whirlpool, then heated the surrounding water to a boil.
8.The villain manipulated the water pressure, then navigated perfectly through the black abyss.
9.The villain sang a distracting melody, then sparked with a static charge.
10.The villain manipulated the water pressure, then disguised the pearl as a common stone.
11.The villain manipulated the water pressure, then sparked with a static charge.
12.The villain sang a distracting melody, then glowed brightly in the dark reef.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Sunken Citadel Mystery
Culprit: Coralia (siren-song · pearl-mimicry · right-wrist bracelet · anemone pink · dried-salt)
- Clue 1 (Fractions of a number): "THE THIEF DOES NOT USE THERMAL VENTING"2/3 of 6 = 4 (T) · 2/3 of 9 = 6 (R) · 3/6 of 66 = 33 (G) · 1/5 of 95 = 19 (U) · 4/8 of 24 = 12 (S) · 2/10 of 115 = 23 (D) · 1/4 of 108 = 27 (H) · 5/10 of 6 = 3 (N) · 1/4 of 84 = 21 (O) · 5/10 of 116 = 58 (I) · 2/5 of 125 = 50 (L) · 4/5 of 50 = 40 (A) · 7/8 of 40 = 35 (M) · 2/8 of 196 = 49 (F) · 1/5 of 195 = 39 (E) · 2/10 of 145 = 29 (V)
- Clue 2 (Place value): "RIGHT WRIST BRACELET MARKINGS FOUND"What is the value of the 2 in 842,346? = 2000 (R) · What is the value of the 9 in 710,691? = 90 (I) · What is the value of the 6 in 72,618? = 600 (G) · What is the value of the 5 in 33,504? = 500 (H) · What is the value of the 4 in 70,347? = 40 (O) · What is the value of the 8 in 58,756? = 8000 (T) · What is the value of the 3 in 247,379? = 300 (A) · What is the value of the 9 in 29,062? = 9000 (F) · What is the value of the 8 in 41,285? = 80 (L) · What is the value of the 2 in 49,287? = 200 (W) · What is the value of the 9 in 74,922? = 900 (S) · What is the value of the 3 in 153,475? = 3000 (B) · What is the value of the 5 in 35,196? = 5000 (K) · What is the value of the 7 in 28,275? = 70 (D) · What is the value of the 1 in 901,947? = 1000 (M) · What is the value of the 2 in 41,525? = 20 (U) · What is the value of the 4 in 57,491? = 400 (N) · What is the value of the 4 in 84,938? = 4000 (C) · What is the value of the 5 in 32,350? = 50 (E)
- Clue 3 (Multiplication facts (1-12)): "THE THIEF AVOIDS DRIED SALT"8 × 2 = 16 (T) · 1 × 10 = 10 (L) · 9 × 1 = 9 (D) · 11 × 8 = 88 (O) · 7 × 12 = 84 (A) · 11 × 6 = 66 (R) · 7 × 7 = 49 (I) · 10 × 2 = 20 (V) · 5 × 10 = 50 (E) · 5 × 5 = 25 (S) · 6 × 6 = 36 (F) · 9 × 3 = 27 (H)
- Clue 4 (Word problems): "ANEMONE PINK"There were 67 luminescent kelp. 4 were used up. How many luminescent kelp are left? = 63 (A) · There were 120 pearls. 3 were used up. How many pearls are left? = 117 (I) · Tide-hunter found 89 coral shards yesterday and 2 more today. How many coral shards in all? = 91 (N) · There were 136 luminescent kelp. 20 were used up. How many luminescent kelp are left? = 116 (E) · Tide-hunter found 2 coral shards yesterday and 59 more today. How many coral shards in all? = 61 (M) · There were 32 coral shards. 13 were used up. How many coral shards are left? = 19 (P) · There were 106 coral shards. 24 were used up. How many coral shards are left? = 82 (O)
- Clue 5 (Fractions of a number): surviving statement (box 3) → Coralia1/8 of 32 = 4 · 1/5 of 45 = 9 · 1/3 of 30 = 10 · 1/2 of 4 = 2 · 2/4 of 22 = 11 · 3/6 of 16 = 8 · 3/8 of 32 = 12 · 1/3 of 3 = 1 · 1/2 of 10 = 5 · 1/4 of 28 = 7 · 5/10 of 12 = 6
About this mystery
- Grade level
- Grade 8 math
- Math topics
- Fractions of a number, Place value, Multiplication, Word problems
- Reading level
- grades 7-9
- Theme
- The Sunken Citadel Mystery — set in the luminescent deep-sea city of Aquamarina
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects