🌊 MermaidsGrade 3Reading: grades 3-4MultiplicationRoundingAdditionSubtractionDivision

The Mystery of the Missing Pearl Crown

Queen Coralia's glowing pearl crown was snatched right from the palace vault! Detective Fin needs your help to decode clues, clear innocent mermaids, and catch the sneaky pearl thief.

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	Magic Tool	Sea Pet	Dominant Fin	Tail Color	Fear
Caspian Depth	Kelp Lasso	Dolphin Companion	Left Fin	Ruby Red Tail	Bright Flashlights
Bubbles Waters	Neptune Trident	Seahorse Buddy	Left Fin	Ruby Red Tail	Tickly Sea Anemones
Shellie Sands	Pearl Staff	Seahorse Buddy	Left Fin	Ruby Red Tail	Loud Foghorns
Ariel Foam	Neptune Trident	Crab Sidekick	Right Fin	Emerald Green Tail	Bright Flashlights
Shelly Shore	Shell Wand	Seahorse Buddy	Left Fin	Ruby Red Tail	Loud Foghorns
Brook River	Pearl Staff	Seahorse Buddy	Left Fin	Ruby Red Tail	Bright Flashlights
Starla Kelp	Shell Wand	Jellyfish Friend	Right Fin	Sapphire Blue Tail	Tickly Sea Anemones
Nixie Lagoon	Starfish Scepter	Seahorse Buddy	Right Fin	Emerald Green Tail	Bright Flashlights
Ocean Spray	Kelp Lasso	Dolphin Companion	Left Fin	Sapphire Blue Tail	Bright Flashlights
Reef Swimmer	Kelp Lasso	Jellyfish Friend	Right Fin	Ruby Red Tail	Loud Foghorns
Sandy Bottom	Kelp Lasso	Jellyfish Friend	Right Fin	Emerald Green Tail	Tickly Sea Anemones
Delphine Blue	Pearl Staff	Sea Turtle Pet	Left Fin	Ruby Red Tail	Bright Flashlights
Ray Manta	Shell Wand	Dolphin Companion	Left Fin	Ruby Red Tail	Loud Foghorns
Cleo Conch	Pearl Staff	Jellyfish Friend	Left Fin	Sapphire Blue Tail	Tickly Sea Anemones
Pearl Glimmer	Neptune Trident	Crab Sidekick	Left Fin	Emerald Green Tail	Bright Flashlights
Kai Tide	Neptune Trident	Seahorse Buddy	Left Fin	Ruby Red Tail	Loud Foghorns
Triton Waves	Kelp Lasso	Seahorse Buddy	Left Fin	Sapphire Blue Tail	Loud Foghorns
Wade Shallow	Neptune Trident	Sea Turtle Pet	Left Fin	Ruby Red Tail	Loud Foghorns
Urchin Pike	Kelp Lasso	Sea Turtle Pet	Right Fin	Sapphire Blue Tail	Tickly Sea Anemones
Coral Reef	Shell Wand	Jellyfish Friend	Right Fin	Sapphire Blue Tail	Bright Flashlights
Finn Current	Shell Wand	Sea Turtle Pet	Right Fin	Emerald Green Tail	Loud Foghorns

Clue 1

Multiplication facts (1-12)

Detective Fin counts equal rows of shiny clam shells near the vault to find the first cipher code.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

132

10 × 9 =T

7 × 11 =H

6 × 5 =N

5 × 3 =L

10 × 7 =R

5 × 5 =E

1 × 4 =S

4 × 9 =U

11 × 12 =O

8 × 8 =Y

6 × 3 =A

7 × 4 =I

9 × 3 =K

6 × 7 =P

12 × 8 =F

0/15 letters found

Clue 2

Rounding

The royal sonar radar rounds the distance to the thief's getaway path to give a quick estimate.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

4000

400

5000

9000

5000

800

4000

700

4000

400

4000

400

5000

700

7000

5000

500

4000

500

700

3000

Round 4,316 to the nearest thousandT

Round 9,495 to the nearest thousandU

Round 77 to the nearest tenP

Round 454 to the nearest hundredF

Round 4,672 to the nearest thousandE

Round 3,195 to the nearest thousandN

Round 775 to the nearest hundredC

Round 70 to the nearest tenM

Round 383 to the nearest hundredH

Round 717 to the nearest hundredI

Round 6,620 to the nearest thousandR

Round 30 to the nearest tenL

Round 62 to the nearest tenS

Round 43 to the nearest tenW

0/14 letters found

Clue 3

Addition

Fin gathers up all the loose pearls dropped in the hallway and adds them to his clue pouch.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

874

571

638

706

201

571

546

796

571

358

671

470

706

358

571

657

779

444

796

779

444

796

988

779

201

607

384

576

227

526 + 348 =L

373 + 203 =C

485 + 221 =D

349 + 258 =B

233 + 125 =R

380 + 291 =N

151 + 76 =K

300 + 271 =O

255 + 215 =S

285 + 353 =U

144 + 300 =T

456 + 201 =V

426 + 353 =E

202 + 182 =A

474 + 322 =H

79 + 122 =F

222 + 324 =G

298 + 690 =I

0/18 letters found

Clue 4

Subtraction

The palace guard checks how many sea crystals are left after the thief scrambled away.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

199

518

197

859

161

194

813

363

390

161

208

540

390

518

813

443

363

246

169

149

808

363

169

518

241 - 42 =W

400 - 203 =F

708 - 318 =R

574 - 328 =I

415 - 221 =N

917 - 104 =D

809 - 291 =E

626 - 86 =Y

198 - 49 =S

189 - 28 =U

692 - 249 =T

496 - 327 =L

896 - 37 =O

401 - 38 =A

1166 - 358 =C

502 - 294 =B

0/16 letters found

Clue 5

Division facts (1-12) — the last clue

Fin splits the sea snails evenly into glass jars to reveal the final secret message.

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

40 ÷ 4 = ?

48 ÷ 6 = ?

18 ÷ 6 = ?

36 ÷ 6 = ?

49 ÷ 7 = ?

10 ÷ 10 = ?

36 ÷ 3 = ?

20 ÷ 5 = ?

77 ÷ 7 = ?

60 ÷ 12 = ?

14 ÷ 7 = ?

Step 2 — cross out the sentence with each answer

1.The villain cast a beam with a scepter, then scuttled off with a crab sidekick.

2.The villain tapped a pearl staff on the gate, then rode off with a dolphin companion.

3.The villain waved a magical shell wand, then rode off with a dolphin companion.

4.The villain cast a beam with a scepter, then darted off with a seahorse buddy.

5.The villain tapped a pearl staff on the gate, then scuttled off with a crab sidekick.

6.The villain waved a magical shell wand, then floated away with a jellyfish friend.

7.The villain twirled a kelp lasso around, then zipped away with a sea turtle pet.

8.The villain waved a magical shell wand, then darted off with a seahorse buddy.

9.The villain tapped a pearl staff on the gate, then darted off with a seahorse buddy.

10.The villain zapped the vault with a trident, then darted off with a seahorse buddy.

11.The villain twirled a kelp lasso around, then rode off with a dolphin companion.

12.The villain waved a magical shell wand, then zipped away with a sea turtle pet.

Solve it

Name the culprit

Choose the one suspect left standing.

Answer Key — The Mystery of the Missing Pearl Crown

Culprit: Shellie Sands (Pearl Staff · Seahorse Buddy · Left Fin · Ruby Red Tail · Loud Foghorns)

Clue 1 (Multiplication facts (1-12)): "THE SNEAKY THIEF HAS NO SEA TURTLE PET"
10 × 9 = 90 (T) · 7 × 11 = 77 (H) · 6 × 5 = 30 (N) · 5 × 3 = 15 (L) · 10 × 7 = 70 (R) · 5 × 5 = 25 (E) · 1 × 4 = 4 (S) · 4 × 9 = 36 (U) · 11 × 12 = 132 (O) · 8 × 8 = 64 (Y) · 6 × 3 = 18 (A) · 7 × 4 = 28 (I) · 9 × 3 = 27 (K) · 6 × 7 = 42 (P) · 12 × 8 = 96 (F)
Clue 2 (Rounding): "THE SUSPECT SWIMS WITH THEIR LEFT FIN"
Round 4,316 to the nearest thousand = 4000 (T) · Round 9,495 to the nearest thousand = 9000 (U) · Round 77 to the nearest ten = 80 (P) · Round 454 to the nearest hundred = 500 (F) · Round 4,672 to the nearest thousand = 5000 (E) · Round 3,195 to the nearest thousand = 3000 (N) · Round 775 to the nearest hundred = 800 (C) · Round 70 to the nearest ten = 70 (M) · Round 383 to the nearest hundred = 400 (H) · Round 717 to the nearest hundred = 700 (I) · Round 6,620 to the nearest thousand = 7000 (R) · Round 30 to the nearest ten = 30 (L) · Round 62 to the nearest ten = 60 (S) · Round 43 to the nearest ten = 40 (W)
Clue 3 (Addition): "LOUD FOGHORNS DROVE THE THIEF BACK"
526 + 348 = 874 (L) · 373 + 203 = 576 (C) · 485 + 221 = 706 (D) · 349 + 258 = 607 (B) · 233 + 125 = 358 (R) · 380 + 291 = 671 (N) · 151 + 76 = 227 (K) · 300 + 271 = 571 (O) · 255 + 215 = 470 (S) · 285 + 353 = 638 (U) · 144 + 300 = 444 (T) · 456 + 201 = 657 (V) · 426 + 353 = 779 (E) · 202 + 182 = 384 (A) · 474 + 322 = 796 (H) · 79 + 122 = 201 (F) · 222 + 324 = 546 (G) · 298 + 690 = 988 (I)
Clue 4 (Subtraction): "WE FOUND A RUBY RED TAIL SCALE"
241 - 42 = 199 (W) · 400 - 203 = 197 (F) · 708 - 318 = 390 (R) · 574 - 328 = 246 (I) · 415 - 221 = 194 (N) · 917 - 104 = 813 (D) · 809 - 291 = 518 (E) · 626 - 86 = 540 (Y) · 198 - 49 = 149 (S) · 189 - 28 = 161 (U) · 692 - 249 = 443 (T) · 496 - 327 = 169 (L) · 896 - 37 = 859 (O) · 401 - 38 = 363 (A) · 1166 - 358 = 808 (C) · 502 - 294 = 208 (B)
Clue 5 (Division facts (1-12)): surviving statement (box 9) → Shellie Sands
40 ÷ 4 = 10 · 48 ÷ 6 = 8 · 18 ÷ 6 = 3 · 36 ÷ 6 = 6 · 49 ÷ 7 = 7 · 10 ÷ 10 = 1 · 36 ÷ 3 = 12 · 20 ÷ 5 = 4 · 77 ÷ 7 = 11 · 60 ÷ 12 = 5 · 14 ÷ 7 = 2

About this mystery

Grade level: Grade 3 math
Math topics: Multiplication, Rounding, Addition, Subtraction, Division
Reading level: grades 3-4
Theme: The Mystery of the Missing Pearl Crown — set in The Coral Kingdom of Aquaria
Format: Interactive online & printable worksheet with answer key
Solution: One unique, verified culprit among 21 suspects

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