🌊 MermaidsGrade 5Reading: grades 5-6Fractions of a numberOrder of operationsMultiplicationRoundingDivision
The Case of the Missing Royal Pearl
When the Great Glowing Pearl vanishes from the Sunken Vault, the Coral Reef Guard calls upon you to track down the thief using ocean clues and math evidence.
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 | Trident Magic | Ocean Artifact | Swimming Habit | Fin Color | Disliked Sound |
|---|---|---|---|---|---|
| Tidus | Wave Whisper | Prism Shell | Right Fin Striker | Deep Sapphire | Dolphin Whistle |
| Thallas | Bubble Blast | Starfish Compass | Left Fin Striker | Coral Crimson | Ship Bell Ring |
| Nixie | Current Charm | Glowing Conch | Left Fin Striker | Coral Crimson | Dolphin Whistle |
| Kelpie | Bubble Blast | Seaweed Lasso | Left Fin Striker | Coral Crimson | Ship Bell Ring |
| Coralia | Bubble Blast | Seaweed Lasso | Left Fin Striker | Deep Sapphire | Ship Bell Ring |
| Muriel | Wave Whisper | Glowing Conch | Left Fin Striker | Deep Sapphire | Dolphin Whistle |
| Maren | Tidal Surge | Coral Mirror | Left Fin Striker | Deep Sapphire | Ship Bell Ring |
| Sirena | Current Charm | Glowing Conch | Left Fin Striker | Deep Sapphire | Foghorn Blast |
| Ariel | Hydro Shield | Glowing Conch | Right Fin Striker | Deep Sapphire | Dolphin Whistle |
| Delphine | Tidal Surge | Starfish Compass | Right Fin Striker | Emerald Green | Ship Bell Ring |
| Coral | Current Charm | Starfish Compass | Left Fin Striker | Emerald Green | Dolphin Whistle |
| Triton | Current Charm | Glowing Conch | Right Fin Striker | Deep Sapphire | Ship Bell Ring |
| Kai | Wave Whisper | Prism Shell | Left Fin Striker | Deep Sapphire | Dolphin Whistle |
| Naida | Bubble Blast | Prism Shell | Left Fin Striker | Coral Crimson | Dolphin Whistle |
| Selkie | Tidal Surge | Starfish Compass | Left Fin Striker | Deep Sapphire | Dolphin Whistle |
| Marina | Current Charm | Prism Shell | Left Fin Striker | Coral Crimson | Ship Bell Ring |
| Nerida | Tidal Surge | Starfish Compass | Right Fin Striker | Coral Crimson | Dolphin Whistle |
| Oceanus | Wave Whisper | Seaweed Lasso | Left Fin Striker | Deep Sapphire | Dolphin Whistle |
| Pearl | Tidal Surge | Prism Shell | Left Fin Striker | Coral Crimson | Foghorn Blast |
| Caspian | Tidal Surge | Coral Mirror | Left Fin Striker | Deep Sapphire | Dolphin Whistle |
| Tritonus | Bubble Blast | Coral Mirror | Right Fin Striker | Deep Sapphire | Dolphin Whistle |
Clue 1
Fractions of a number
The Vault Keeper examined the inventory ledger where only a fraction of the royal pearls remained unaccounted for.
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
18
23
10
39
12
29
29
34
12
4
33
36
10
28
4
36
T
18
38
28
10
34
26
27
12
28
3
28
23
10
29
29
6/8 of 24 =T
1/5 of 115 =H
2/6 of 12 =N
1/4 of 156 =V
2/10 of 180 =O
2/5 of 65 =P
1/6 of 168 =S
5/10 of 54 =R
2/6 of 87 =L
1/3 of 99 =D
4/6 of 51 =A
4/8 of 76 =U
2/6 of 36 =I
1/2 of 20 =E
2/10 of 15 =M
0/15 letters found
Clue 2
Order of operations
To decode the lock matrix on the ancient reef safe you must evaluate the multi step magic sequence in order.
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
40
52
53
46
44
46
41
53
31
T
40
18
12
46
46
53
53
14
44
46
56
14
42
12
39
53
27
T
40
27
56
14
46
T
40
78
56
7
53
12 × 4 - 8 =T
46 + 4 × 8 =R
9 × 6 - 8 =S
1 + 2 × 3 =K
2 + 5 × 2 =A
6 × 9 - 12 =G
2 + 6 × 2 =N
9 × 6 - 2 =H
10 × 5 - 19 =C
5 × 9 - 27 =W
37 + 2 × 2 =P
11 × 7 - 21 =I
4 + 8 × 5 =U
11 × 4 - 17 =F
10 × 5 - 11 =L
8 × 10 - 27 =E
0/16 letters found
Clue 3
Multiplication facts (1-12)
The guard counted rows of glowing sea crystals stacked along the cavern walls to estimate the thief path.
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
54
6
56
20
100
55
55
45
100
15
70
99
45
121
100
50
66
45
100
55
56
7
15
56
45
33
45
7
11
55
42
6
100
15
48
6
100
70
T
54
55
56
6 × 9 =T
8 × 7 =E
11 × 9 =M
11 × 5 =L
11 × 1 =O
5 × 9 =A
1 × 6 =H
1 × 7 =D
5 × 10 =C
11 × 6 =F
10 × 10 =I
11 × 11 =G
4 × 5 =V
6 × 7 =P
3 × 11 =R
5 × 3 =N
10 × 7 =S
12 × 4 =W
0/18 letters found
Clue 4
Rounding
The sonar display at the guard station rounded the depth measurements to the nearest ten fathoms.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
S
1300
9000
2000
700
130
S
1300
700
130
5000
30
3000
130
170
70
1100
300
S
1300
170
70
20
20
130
430
130
300
300
130
130
900
S
1300
2000
900
900
170
70
430
130
Round 1,338 to the nearest hundredS
Round 23 to the nearest tenM
Round 134 to the nearest tenE
Round 299 to the nearest hundredD
Round 168 to the nearest tenH
Round 2,039 to the nearest thousandA
Round 68 to the nearest tenI
Round 8,919 to the nearest thousandC
Round 31 to the nearest tenT
Round 433 to the nearest tenR
Round 747 to the nearest hundredL
Round 4,696 to the nearest thousandF
Round 3,380 to the nearest thousandB
Round 1,094 to the nearest hundredN
Round 916 to the nearest hundredP
0/15 letters found
Clue 5
Division facts (1-12) — the last clue
The detective split the recovered shell tokens equally among the underwater search squads.
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
60 ÷ 5 = ?
36 ÷ 12 = ?
8 ÷ 8 = ?
48 ÷ 8 = ?
8 ÷ 2 = ?
20 ÷ 4 = ?
45 ÷ 5 = ?
49 ÷ 7 = ?
24 ÷ 12 = ?
40 ÷ 5 = ?
80 ÷ 8 = ?
Step 2 — cross out the sentence with each answer
1.The villain summoned a tidal surge, then lifted a coral mirror.
2.The villain launched a bubble blast, then swung a seaweed lasso.
3.The villain summoned a tidal surge, then consulted a starfish compass.
4.The villain cast a hydro shield, then consulted a starfish compass.
5.The villain summoned a tidal surge, then shined a prism shell.
6.The villain wove a current charm, then consulted a starfish compass.
7.The villain launched a bubble blast, then lifted a coral mirror.
8.The villain summoned a tidal surge, then swung a seaweed lasso.
9.The villain launched a bubble blast, then shined a prism shell.
10.The villain called a wave whisper, then shined a prism shell.
11.The villain called a wave whisper, then flashed a glowing conch.
12.The villain called a wave whisper, then swung a seaweed lasso.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Case of the Missing Royal Pearl
Culprit: Muriel (Wave Whisper · Glowing Conch · Left Fin Striker · Deep Sapphire · Dolphin Whistle)
- Clue 1 (Fractions of a number): "THE VILLAIN DOES NOT USE A PRISM SHELL"6/8 of 24 = 18 (T) · 1/5 of 115 = 23 (H) · 2/6 of 12 = 4 (N) · 1/4 of 156 = 39 (V) · 2/10 of 180 = 36 (O) · 2/5 of 65 = 26 (P) · 1/6 of 168 = 28 (S) · 5/10 of 54 = 27 (R) · 2/6 of 87 = 29 (L) · 1/3 of 99 = 33 (D) · 4/6 of 51 = 34 (A) · 4/8 of 76 = 38 (U) · 2/6 of 36 = 12 (I) · 1/2 of 20 = 10 (E) · 2/10 of 15 = 3 (M)
- Clue 2 (Order of operations): "THE SUSPECT WAS SEEN USING A LEFT FIN STRIKE"12 × 4 - 8 = 40 (T) · 46 + 4 × 8 = 78 (R) · 9 × 6 - 8 = 46 (S) · 1 + 2 × 3 = 7 (K) · 2 + 5 × 2 = 12 (A) · 6 × 9 - 12 = 42 (G) · 2 + 6 × 2 = 14 (N) · 9 × 6 - 2 = 52 (H) · 10 × 5 - 19 = 31 (C) · 5 × 9 - 27 = 18 (W) · 37 + 2 × 2 = 41 (P) · 11 × 7 - 21 = 56 (I) · 4 + 8 × 5 = 44 (U) · 11 × 4 - 17 = 27 (F) · 10 × 5 - 11 = 39 (L) · 8 × 10 - 27 = 53 (E)
- Clue 3 (Multiplication facts (1-12)): "THE VILLAINS MAGIC FAILED NEAR A DOLPHIN WHISTLE"6 × 9 = 54 (T) · 8 × 7 = 56 (E) · 11 × 9 = 99 (M) · 11 × 5 = 55 (L) · 11 × 1 = 11 (O) · 5 × 9 = 45 (A) · 1 × 6 = 6 (H) · 1 × 7 = 7 (D) · 5 × 10 = 50 (C) · 11 × 6 = 66 (F) · 10 × 10 = 100 (I) · 11 × 11 = 121 (G) · 4 × 5 = 20 (V) · 6 × 7 = 42 (P) · 3 × 11 = 33 (R) · 5 × 3 = 15 (N) · 10 × 7 = 70 (S) · 12 × 4 = 48 (W)
- Clue 4 (Rounding): "SCALES LEFT BEHIND SHIMMERED DEEP SAPPHIRE"Round 1,338 to the nearest hundred = 1300 (S) · Round 23 to the nearest ten = 20 (M) · Round 134 to the nearest ten = 130 (E) · Round 299 to the nearest hundred = 300 (D) · Round 168 to the nearest ten = 170 (H) · Round 2,039 to the nearest thousand = 2000 (A) · Round 68 to the nearest ten = 70 (I) · Round 8,919 to the nearest thousand = 9000 (C) · Round 31 to the nearest ten = 30 (T) · Round 433 to the nearest ten = 430 (R) · Round 747 to the nearest hundred = 700 (L) · Round 4,696 to the nearest thousand = 5000 (F) · Round 3,380 to the nearest thousand = 3000 (B) · Round 1,094 to the nearest hundred = 1100 (N) · Round 916 to the nearest hundred = 900 (P)
- Clue 5 (Division facts (1-12)): surviving statement (box 11) → Muriel60 ÷ 5 = 12 · 36 ÷ 12 = 3 · 8 ÷ 8 = 1 · 48 ÷ 8 = 6 · 8 ÷ 2 = 4 · 20 ÷ 4 = 5 · 45 ÷ 5 = 9 · 49 ÷ 7 = 7 · 24 ÷ 12 = 2 · 40 ÷ 5 = 8 · 80 ÷ 8 = 10
About this mystery
- Grade level
- Grade 5 math
- Math topics
- Fractions of a number, Order of operations, Multiplication, Rounding, Division
- Reading level
- grades 5-6
- Theme
- The Case of the Missing Royal Pearl — set in Coral Cove Kingdom
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects