🌊 MermaidsGrade 3Reading: grades 3-4AdditionSkip countingPlace valueRoundingDivision
The Mystery of Coral Cove
Someone swiped the Royal Glowing Pearl from the Reef Palace! Inspect the underwater clues and help Commander Fin solve the mystery.
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 | Swim Skill | Tail Magic | Fin Mark | Tail Color | Fear |
|---|---|---|---|---|---|
| Attina | Bubble Shield | Tide Control | Left Fin | Shimmer Pink | Tickle Kelp |
| Ursula | Bubble Shield | Seafoam Blast | Left Fin | Shimmer Pink | Bright Flash |
| Alana | Current Glide | Tide Control | Right Fin | Deep Sapphire | Loud Drums |
| Oceanus | Bubble Shield | Starfish Zap | Right Fin | Deep Sapphire | Tickle Kelp |
| Nixie | Coral Burst | Seafoam Blast | Right Fin | Shimmer Pink | Bright Flash |
| Aquata | Siren Song | Starfish Zap | Left Fin | Emerald Green | Tickle Kelp |
| Poseidon | Siren Song | Glowing Scales | Right Fin | Shimmer Pink | Bright Flash |
| Marina | Wave Dash | Tide Control | Left Fin | Emerald Green | Loud Drums |
| Cleo | Bubble Shield | Seafoam Blast | Right Fin | Shimmer Pink | Loud Drums |
| Ariel | Current Glide | Shell Blast | Right Fin | Deep Sapphire | Loud Drums |
| Caspian | Coral Burst | Tide Control | Right Fin | Deep Sapphire | Loud Drums |
| Melody | Current Glide | Starfish Zap | Right Fin | Deep Sapphire | Loud Drums |
| Sandy | Current Glide | Starfish Zap | Left Fin | Emerald Green | Tickle Kelp |
| Waverly | Siren Song | Glowing Scales | Right Fin | Deep Sapphire | Bright Flash |
| Triton | Wave Dash | Tide Control | Left Fin | Deep Sapphire | Loud Drums |
| Kai | Coral Burst | Glowing Scales | Left Fin | Shimmer Pink | Tickle Kelp |
| Nerida | Wave Dash | Seafoam Blast | Left Fin | Emerald Green | Loud Drums |
| Ondine | Siren Song | Starfish Zap | Right Fin | Deep Sapphire | Loud Drums |
| Arista | Wave Dash | Glowing Scales | Right Fin | Emerald Green | Loud Drums |
| Adella | Siren Song | Starfish Zap | Right Fin | Deep Sapphire | Tickle Kelp |
| Finn | Current Glide | Seafoam Blast | Right Fin | Emerald Green | Loud Drums |
Clue 1
Addition
Commander Fin tallies the broken shells along the sandy reef floor.
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
623
711
361
T
623
711
920
361
950
775
440
361
946
539
440
T
623
969
946
361
946
711
361
309
309
330
309
665
946
T
623
256
665
415
920
314
190 + 433 =T
269 + 146 =G
358 + 592 =F
201 + 129 =B
171 + 368 =N
349 + 620 =U
160 + 96 =M
128 + 181 =L
355 + 591 =S
473 + 302 =D
137 + 177 =C
385 + 280 =A
176 + 185 =E
251 + 189 =O
498 + 213 =H
593 + 327 =I
0/16 letters found
Clue 2
Skip counting
Detective Fin counts sea anemone petals by jumping across the reef ledges.
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
33
65
90
36
6
80
65
40
140
21
65
27
10
140
21
10
R
33
10
140
10
10
40
40
10
14
R
33
6
36
10
18
14
30
10
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, ___, 36, 39R
Skip-count by 10s. Fill the blank: 10, 20, 30, ___, 50, 60N
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, ___, 21, 24C
Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ___, 70, 75I
Skip-count by 10s. Fill the blank: 10, 20, ___, 40, 50V
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, ___, 90, 100F
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, ___, 39, 42H
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, ___, 12, 14E
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, ___, 24, 27W
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160S
Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, ___, 100, 110G
Skip-count by 2s. Fill the blank: 2, 4, ___, 8, 10T
Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, ___, 30, 33P
Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, ___, 16, 18A
0/14 letters found
Clue 3
Place value
Fin inspects the palace gate lock showing ones tens and hundreds.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
L
6000
2000
300
30
30
8000
300
80
10
80
1000
30
4000
40
50
4000
40
50
70
4000
900
10
100
70
80
1000
100
1000
90
What is the value of the 6 in 16,542?L
What is the value of the 1 in 616?S
What is the value of the 3 in 936?D
What is the value of the 8 in 580?M
What is the value of the 1 in 1,396?A
What is the value of the 3 in 377?U
What is the value of the 9 in 5,922?F
What is the value of the 1 in 4,135?W
What is the value of the 4 in 14,621?E
What is the value of the 5 in 8,352?H
What is the value of the 2 in 2,474?O
What is the value of the 7 in 3,678?I
What is the value of the 4 in 143?T
What is the value of the 8 in 78,461?R
What is the value of the 9 in 694?Y
0/15 letters found
Clue 4
Rounding
The sonar reader rounds the ocean depth to the nearest ten.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
D
300
40
40
30
20
60
30
30
50
6000
9000
40
20
90
60
5000
40
20
70
40
5000
5000
60
80
80
50
40
700
60
80
40
Round 323 to the nearest hundredD
Round 93 to the nearest tenC
Round 56 to the nearest tenA
Round 742 to the nearest hundredG
Round 53 to the nearest tenH
Round 43 to the nearest tenE
Round 8,931 to the nearest thousandR
Round 32 to the nearest tenP
Round 21 to the nearest tenS
Round 4,727 to the nearest thousandL
Round 83 to the nearest tenT
Round 70 to the nearest tenF
Round 6,276 to the nearest thousandI
0/13 letters found
Clue 5
Division facts (1-12) — the last clue
Fin splits the gathered shiny sea glass equally among the ocean patrols.
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
14 ÷ 2 = ?
15 ÷ 5 = ?
120 ÷ 12 = ?
12 ÷ 2 = ?
48 ÷ 6 = ?
15 ÷ 3 = ?
36 ÷ 4 = ?
36 ÷ 3 = ?
8 ÷ 4 = ?
48 ÷ 12 = ?
5 ÷ 5 = ?
Step 2 — cross out the sentence with each answer
1.The villain blasted a coral path, then shot shell blasts.
2.The villain blasted a coral path, then fired starfish zaps.
3.The villain glided on ocean currents, then steered the high tide.
4.The villain sang a siren song, then lit up glowing scales.
5.The villain sang a siren song, then created seafoam blasts.
6.The villain dashed through waves, then lit up glowing scales.
7.The villain glided on ocean currents, then fired starfish zaps.
8.The villain sang a siren song, then steered the high tide.
9.The villain glided on ocean currents, then shot shell blasts.
10.The villain sang a siren song, then fired starfish zaps.
11.The villain blasted a coral path, then steered the high tide.
12.The villain sang a siren song, then shot shell blasts.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Mystery of Coral Cove
Culprit: Caspian (Coral Burst · Tide Control · Right Fin · Deep Sapphire · Loud Drums)
- Clue 1 (Addition): "THE THIEF DOES NOT USE SHELL BLAST MAGIC"190 + 433 = 623 (T) · 269 + 146 = 415 (G) · 358 + 592 = 950 (F) · 201 + 129 = 330 (B) · 171 + 368 = 539 (N) · 349 + 620 = 969 (U) · 160 + 96 = 256 (M) · 128 + 181 = 309 (L) · 355 + 591 = 946 (S) · 473 + 302 = 775 (D) · 137 + 177 = 314 (C) · 385 + 280 = 665 (A) · 176 + 185 = 361 (E) · 251 + 189 = 440 (O) · 498 + 213 = 711 (H) · 593 + 327 = 920 (I)
- Clue 2 (Skip counting): "RIGHT FIN SWIPES WERE SEEN NEAR THE CAVE"Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, ___, 36, 39 = 33 (R) · Skip-count by 10s. Fill the blank: 10, 20, 30, ___, 50, 60 = 40 (N) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, ___, 21, 24 = 18 (C) · Skip-count by 5s. Fill the blank: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, ___, 70, 75 = 65 (I) · Skip-count by 10s. Fill the blank: 10, 20, ___, 40, 50 = 30 (V) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, ___, 90, 100 = 80 (F) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, ___, 39, 42 = 36 (H) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, ___, 12, 14 = 10 (E) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, ___, 24, 27 = 21 (W) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, ___, 150, 160 = 140 (S) · Skip-count by 10s. Fill the blank: 10, 20, 30, 40, 50, 60, 70, 80, ___, 100, 110 = 90 (G) · Skip-count by 2s. Fill the blank: 2, 4, ___, 8, 10 = 6 (T) · Skip-count by 3s. Fill the blank: 3, 6, 9, 12, 15, 18, 21, 24, ___, 30, 33 = 27 (P) · Skip-count by 2s. Fill the blank: 2, 4, 6, 8, 10, 12, ___, 16, 18 = 14 (A)
- Clue 3 (Place value): "LOUD DRUMS MADE THE THIEF SWIM AWAY"What is the value of the 6 in 16,542? = 6000 (L) · What is the value of the 1 in 616? = 10 (S) · What is the value of the 3 in 936? = 30 (D) · What is the value of the 8 in 580? = 80 (M) · What is the value of the 1 in 1,396? = 1000 (A) · What is the value of the 3 in 377? = 300 (U) · What is the value of the 9 in 5,922? = 900 (F) · What is the value of the 1 in 4,135? = 100 (W) · What is the value of the 4 in 14,621? = 4000 (E) · What is the value of the 5 in 8,352? = 50 (H) · What is the value of the 2 in 2,474? = 2000 (O) · What is the value of the 7 in 3,678? = 70 (I) · What is the value of the 4 in 143? = 40 (T) · What is the value of the 8 in 78,461? = 8000 (R) · What is the value of the 9 in 694? = 90 (Y)
- Clue 4 (Rounding): "DEEP SAPPHIRE SCALES FELL AT THE GATE"Round 323 to the nearest hundred = 300 (D) · Round 93 to the nearest ten = 90 (C) · Round 56 to the nearest ten = 60 (A) · Round 742 to the nearest hundred = 700 (G) · Round 53 to the nearest ten = 50 (H) · Round 43 to the nearest ten = 40 (E) · Round 8,931 to the nearest thousand = 9000 (R) · Round 32 to the nearest ten = 30 (P) · Round 21 to the nearest ten = 20 (S) · Round 4,727 to the nearest thousand = 5000 (L) · Round 83 to the nearest ten = 80 (T) · Round 70 to the nearest ten = 70 (F) · Round 6,276 to the nearest thousand = 6000 (I)
- Clue 5 (Division facts (1-12)): surviving statement (box 11) → Caspian14 ÷ 2 = 7 · 15 ÷ 5 = 3 · 120 ÷ 12 = 10 · 12 ÷ 2 = 6 · 48 ÷ 6 = 8 · 15 ÷ 3 = 5 · 36 ÷ 4 = 9 · 36 ÷ 3 = 12 · 8 ÷ 4 = 2 · 48 ÷ 12 = 4 · 5 ÷ 5 = 1
About this mystery
- Grade level
- Grade 3 math
- Math topics
- Addition, Skip counting, Place value, Rounding, Division
- Reading level
- grades 3-4
- Theme
- The Mystery of Coral Cove — set in Coral Cove Reef
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects