🌊 MermaidsGrade 3Reading: grades 3-4MultiplicationRoundingAdditionSubtractionDivision

The Great Pearl Reef Heist

A sneaky villain swam into the Royal Vault at Crystal Reef and snatched the Glowing Crown Pearl! The Reef Patrol needs your help to decode the clues, track down the culprit, and save the kingdom.

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	Ocean Move	Mermaid Gear	Dominant Fin	Hair Color	Secret Weakness
Tide	Bubble Blast	Anchor Shield	Right Fin Dominant	Kelp Green	Tickled By Seagrass
Delphin	Current Dash	Glow Tail	Left Fin Dominant	Seafoam Blue	Scared Of Urchins
Kai	Current Dash	Kelp Lasso	Right Fin Dominant	Seafoam Blue	Tickled By Seagrass
Coral	Current Dash	Glow Tail	Right Fin Dominant	Kelp Green	Distracted By Pearls
Caspian	Siren Song	Trident Flash	Left Fin Dominant	Coral Pink	Tickled By Seagrass
Triton	Bubble Blast	Kelp Lasso	Left Fin Dominant	Coral Pink	Distracted By Pearls
Ocean	Tide Turn	Glow Tail	Left Fin Dominant	Seafoam Blue	Tickled By Seagrass
Ray	Whale Whistle	Shell Armor	Left Fin Dominant	Seafoam Blue	Distracted By Pearls
Pearlina	Current Dash	Trident Flash	Right Fin Dominant	Seafoam Blue	Tickled By Seagrass
Bay	Whale Whistle	Shell Armor	Left Fin Dominant	Seafoam Blue	Tickled By Seagrass
Harbor	Bubble Blast	Kelp Lasso	Right Fin Dominant	Seafoam Blue	Tickled By Seagrass
Reef	Siren Song	Glow Tail	Right Fin Dominant	Seafoam Blue	Distracted By Pearls
Coralie	Bubble Blast	Trident Flash	Right Fin Dominant	Kelp Green	Distracted By Pearls
Sandy	Tide Turn	Anchor Shield	Right Fin Dominant	Seafoam Blue	Tickled By Seagrass
Pearl	Current Dash	Glow Tail	Left Fin Dominant	Coral Pink	Scared Of Urchins
Nerida	Tide Turn	Anchor Shield	Left Fin Dominant	Seafoam Blue	Scared Of Urchins
Shelly	Whale Whistle	Glow Tail	Right Fin Dominant	Kelp Green	Distracted By Pearls
Urchin	Whale Whistle	Kelp Lasso	Right Fin Dominant	Seafoam Blue	Tickled By Seagrass
Pacifica	Tide Turn	Anchor Shield	Left Fin Dominant	Kelp Green	Distracted By Pearls
Finn	Tide Turn	Glow Tail	Right Fin Dominant	Seafoam Blue	Scared Of Urchins
Marina	Tide Turn	Glow Tail	Right Fin Dominant	Kelp Green	Tickled By Seagrass

Clue 1

Multiplication facts (1-12)

You count the neat rows of clam shells planted around the vault entrance to unlock the first clue vault.

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

108

9 × 7 =T

4 × 7 =F

5 × 5 =E

8 × 5 =C

8 × 8 =L

8 × 10 =H

1 × 5 =D

12 × 8 =U

9 × 12 =R

5 × 6 =O

4 × 1 =P

9 × 10 =S

7 × 8 =A

11 × 5 =N

3 × 3 =I

0/15 letters found

Clue 2

Rounding

The glowing ocean radar rounds off the water depth to the nearest ten meters so you can read the next secret note.

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

7000

200

5000

2000

200

400

300

7000

4000

400

3000

300

7000

5000

3000

600

3000

300

7000

500

300

8000

500

Round 7,462 to the nearest thousandR

Round 2,192 to the nearest thousandF

Round 4,677 to the nearest thousandH

Round 56 to the nearest tenV

Round 81 to the nearest tenT

Round 331 to the nearest hundredA

Round 2,780 to the nearest thousandE

Round 94 to the nearest tenG

Round 226 to the nearest hundredI

Round 424 to the nearest hundredN

Round 8,487 to the nearest thousandU

Round 539 to the nearest hundredL

Round 40 to the nearest tenK

Round 643 to the nearest hundredP

Round 4,104 to the nearest thousandS

Round 24 to the nearest tenM

0/16 letters found

Clue 3

Addition

You tally up all the shiny scales found across three different coral beds to piece together the third evidence report.

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

434

913

452

660

858

452

434

703

363

846

380

465

913

434

740

452

742

913

371

363

465

452

363

635

434

819

465

913

303 + 131 =S

498 + 244 =D

507 + 233 =M

430 + 416 =C

234 + 426 =G

403 + 300 =T

386 + 433 =F

370 + 265 =N

137 + 226 =I

221 + 159 =K

239 + 132 =V

196 + 256 =A

175 + 290 =L

367 + 491 =R

553 + 360 =E

0/15 letters found

Clue 4

Subtraction

By checking how many pearls remain in the royal treasure chest compared to yesterday, you reveal clue four.

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

687

567

833

125

389

125

645

387

609

645

287

489

645

678

867

694

867

678

387

750

125

694

678

258

750

678

694

125

990 - 303 =B

609 - 222 =F

494 - 5 =H

1052 - 358 =D

626 - 59 =L

1135 - 385 =T

413 - 155 =N

812 - 134 =I

794 - 185 =O

1068 - 235 =U

279 - 154 =E

411 - 124 =M

566 - 177 =S

861 - 216 =A

956 - 89 =R

0/15 letters found

Clue 5

Division facts (1-12) — the last clue

The Reef Patrol splits up the glowing sea crystals equally among the team to power up the final hint scanner.

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

72 ÷ 9 = ?

120 ÷ 10 = ?

6 ÷ 1 = ?

77 ÷ 11 = ?

3 ÷ 1 = ?

24 ÷ 6 = ?

120 ÷ 12 = ?

16 ÷ 8 = ?

50 ÷ 10 = ?

1 ÷ 1 = ?

81 ÷ 9 = ?

Step 2 — cross out the sentence with each answer

1.The villain sang a hypnotic siren song, then created a bright trident flash.

2.The villain blasted a cloud of bubbles, then flashed a brightly glowing tail.

3.The villain turned the tide around, then flashed a brightly glowing tail.

4.The villain dashed through the current, then flashed a brightly glowing tail.

5.The villain blew a loud whale whistle, then flashed a brightly glowing tail.

6.The villain blew a loud whale whistle, then swung a kelp lasso.

7.The villain blew a loud whale whistle, then ducked behind shell armor.

8.The villain turned the tide around, then blocked the doorway with an anchor shield.

9.The villain blasted a cloud of bubbles, then ducked behind shell armor.

10.The villain dashed through the current, then created a bright trident flash.

11.The villain dashed through the current, then swung a kelp lasso.

12.The villain blasted a cloud of bubbles, then swung a kelp lasso.

Solve it

Name the culprit

Choose the one suspect left standing.

Answer Key — The Great Pearl Reef Heist

Culprit: Kai (Current Dash · Kelp Lasso · Right Fin Dominant · Seafoam Blue · Tickled By Seagrass)

Clue 1 (Multiplication facts (1-12)): "THE SUSPECT DOES NOT USE TRIDENT FLASH"
9 × 7 = 63 (T) · 4 × 7 = 28 (F) · 5 × 5 = 25 (E) · 8 × 5 = 40 (C) · 8 × 8 = 64 (L) · 8 × 10 = 80 (H) · 1 × 5 = 5 (D) · 12 × 8 = 96 (U) · 9 × 12 = 108 (R) · 5 × 6 = 30 (O) · 4 × 1 = 4 (P) · 9 × 10 = 90 (S) · 7 × 8 = 56 (A) · 11 × 5 = 55 (N) · 3 × 3 = 9 (I)
Clue 2 (Rounding): "RIGHT FIN MARKS NEAR THE PEARL VAULT"
Round 7,462 to the nearest thousand = 7000 (R) · Round 2,192 to the nearest thousand = 2000 (F) · Round 4,677 to the nearest thousand = 5000 (H) · Round 56 to the nearest ten = 60 (V) · Round 81 to the nearest ten = 80 (T) · Round 331 to the nearest hundred = 300 (A) · Round 2,780 to the nearest thousand = 3000 (E) · Round 94 to the nearest ten = 90 (G) · Round 226 to the nearest hundred = 200 (I) · Round 424 to the nearest hundred = 400 (N) · Round 8,487 to the nearest thousand = 8000 (U) · Round 539 to the nearest hundred = 500 (L) · Round 40 to the nearest ten = 40 (K) · Round 643 to the nearest hundred = 600 (P) · Round 4,104 to the nearest thousand = 4000 (S) · Round 24 to the nearest ten = 20 (M)
Clue 3 (Addition): "SEAGRASS TICKLES MADE VILLAINS FLEE"
303 + 131 = 434 (S) · 498 + 244 = 742 (D) · 507 + 233 = 740 (M) · 430 + 416 = 846 (C) · 234 + 426 = 660 (G) · 403 + 300 = 703 (T) · 386 + 433 = 819 (F) · 370 + 265 = 635 (N) · 137 + 226 = 363 (I) · 221 + 159 = 380 (K) · 239 + 132 = 371 (V) · 196 + 256 = 452 (A) · 175 + 290 = 465 (L) · 367 + 491 = 858 (R) · 553 + 360 = 913 (E)
Clue 4 (Subtraction): "BLUE SEAFOAM HAIR DRIFTED IN TIDE"
990 - 303 = 687 (B) · 609 - 222 = 387 (F) · 494 - 5 = 489 (H) · 1052 - 358 = 694 (D) · 626 - 59 = 567 (L) · 1135 - 385 = 750 (T) · 413 - 155 = 258 (N) · 812 - 134 = 678 (I) · 794 - 185 = 609 (O) · 1068 - 235 = 833 (U) · 279 - 154 = 125 (E) · 411 - 124 = 287 (M) · 566 - 177 = 389 (S) · 861 - 216 = 645 (A) · 956 - 89 = 867 (R)
Clue 5 (Division facts (1-12)): surviving statement (box 11) → Kai
72 ÷ 9 = 8 · 120 ÷ 10 = 12 · 6 ÷ 1 = 6 · 77 ÷ 11 = 7 · 3 ÷ 1 = 3 · 24 ÷ 6 = 4 · 120 ÷ 12 = 10 · 16 ÷ 8 = 2 · 50 ÷ 10 = 5 · 1 ÷ 1 = 1 · 81 ÷ 9 = 9

About this mystery

Grade level: Grade 3 math
Math topics: Multiplication, Rounding, Addition, Subtraction, Division
Reading level: grades 3-4
Theme: The Great Pearl Reef Heist — set in The Crystal Sunken Palace
Format: Interactive online & printable worksheet with answer key
Solution: One unique, verified culprit among 21 suspects

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