🌊 MermaidsGrade 3Reading: grades 3-4RoundingAdditionSubtractionMultiplicationDivision
The Case of the Missing Star Pearl
Someone snatched the Royal Star Pearl right before the Sunken Festival! Detective Bubbles needs your help to decode the clues, check the suspect roster, and catch the sneaky mermaid 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 | Trident Skill | Sea Companion | Flippers | Fin Color | Weakness |
|---|---|---|---|---|---|
| Thalia Harbor | Glow Sparkle | Sea Turtle | Left Finned | Deep Blue | Sticky Kelp |
| Delphine Shell | Song Magic | Glowing Squid | Left Finned | Deep Blue | Sticky Kelp |
| Calypso Trench | Bubble Shields | Hermit Crab | Left Finned | Deep Blue | Bright Flash |
| Cordelia Bay | Wave Calling | Glowing Squid | Left Finned | Aqua Green | Bright Flash |
| Nereus Swell | Current Control | Sea Turtle | Left Finned | Coral Pink | Bright Flash |
| Triton Tide | Current Control | Glowing Squid | Right Finned | Aqua Green | Loud Shells |
| Pearl Wave | Wave Calling | Sea Turtle | Right Finned | Coral Pink | Bright Flash |
| Shelly Lagoon | Glow Sparkle | Dolphin Pal | Left Finned | Aqua Green | Sticky Kelp |
| Kai Current | Bubble Shields | Dolphin Pal | Right Finned | Aqua Green | Sticky Kelp |
| Oceanus Blue | Song Magic | Dolphin Pal | Right Finned | Coral Pink | Sticky Kelp |
| Caspian Kelp | Song Magic | Hermit Crab | Left Finned | Coral Pink | Bright Flash |
| Maren Deep | Current Control | Sea Turtle | Left Finned | Deep Blue | Sticky Kelp |
| Marina Pearl | Bubble Shields | Glowing Squid | Left Finned | Deep Blue | Loud Shells |
| Nerida Splash | Wave Calling | Hermit Crab | Left Finned | Aqua Green | Sticky Kelp |
| Coral Reef | Song Magic | Dolphin Pal | Left Finned | Deep Blue | Sticky Kelp |
| Pearl Ripple | Current Control | Dolphin Pal | Left Finned | Coral Pink | Loud Shells |
| Finnegan Grotto | Glow Sparkle | Hermit Crab | Left Finned | Aqua Green | Loud Shells |
| Siren Drift | Current Control | Hermit Crab | Left Finned | Deep Blue | Loud Shells |
| Azure Abyss | Current Control | Hermit Crab | Left Finned | Deep Blue | Sticky Kelp |
| Sandy Shoal | Current Control | Sea Turtle | Right Finned | Deep Blue | Sticky Kelp |
| Muriel Star | Glow Sparkle | Dolphin Pal | Left Finned | Coral Pink | Sticky Kelp |
Clue 1
Rounding
The grotto sonar radar rounded the blips to the nearest hundred to track the thief.
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
20
500
7000
200
800
8000
8000
90
800
600
900
80
7000
300
600
80
T
20
500
90
200
7000
90
70
8000
80
5000
800
600
70
300
3000
2000
800
900
Round 17 to the nearest tenT
Round 7,389 to the nearest thousandE
Round 7,617 to the nearest thousandL
Round 899 to the nearest hundredD
Round 1,878 to the nearest thousandU
Round 581 to the nearest hundredN
Round 755 to the nearest hundredI
Round 83 to the nearest tenO
Round 86 to the nearest tenA
Round 455 to the nearest hundredH
Round 170 to the nearest hundredV
Round 4,538 to the nearest thousandW
Round 297 to the nearest hundredS
Round 2,517 to the nearest thousandQ
Round 70 to the nearest tenG
0/15 letters found
Clue 2
Addition
Detective Bubbles added up all the scattered shell coins left behind on the ocean 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.
W
645
608
837
617
304
941
941
304
941
941
283
W
645
283
653
304
287
837
287
608
617
617
304
695
941
W
645
608
658
658
304
465
216 + 429 =W
551 + 390 =S
151 + 136 =F
92 + 191 =A
230 + 423 =L
322 + 373 =D
387 + 450 =T
314 + 294 =I
120 + 184 =E
316 + 149 =R
317 + 341 =M
270 + 347 =N
0/12 letters found
Clue 3
Subtraction
The guards subtracted the missing glowing pearls from the vault inventory total.
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
655
169
260
T
655
169
657
260
364
220
883
T
655
T
655
284
612
220
130
260
785
657
612
516
T
655
657
774
187
216
187
260
130
780
867 - 212 =T
707 - 191 =S
824 - 39 =D
433 - 173 =E
385 - 21 =F
1001 - 344 =I
1073 - 190 =O
374 - 158 =Y
887 - 107 =P
376 - 246 =L
208 - 21 =K
838 - 226 =N
524 - 355 =H
343 - 59 =A
933 - 159 =C
563 - 343 =G
0/16 letters found
Clue 4
Multiplication facts (1-12)
The sea turtles swam in equal rows to search the coral reef grids.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
B
108
35
40
4
80
63
8
35
4
80
11
4
144
4
99
144
33
90
90
4
99
6
4
8
144
120
54
4
80
8
81
4
9 × 12 =B
11 × 3 =O
12 × 10 =T
10 × 4 =U
9 × 10 =P
12 × 12 =R
10 × 8 =S
9 × 6 =H
1 × 6 =N
8 × 1 =A
11 × 9 =D
9 × 9 =F
4 × 1 =E
1 × 11 =W
9 × 7 =C
5 × 7 =L
0/16 letters found
Clue 5
Division facts (1-12) — the last clue
The clam guards split the recovered kelp snacks evenly among their patrol groups.
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
33 ÷ 11 = ?
15 ÷ 3 = ?
70 ÷ 10 = ?
10 ÷ 1 = ?
64 ÷ 8 = ?
32 ÷ 8 = ?
66 ÷ 11 = ?
2 ÷ 1 = ?
27 ÷ 3 = ?
3 ÷ 3 = ?
66 ÷ 6 = ?
Step 2 — cross out the sentence with each answer
1.The villain blasted bubble shields, then lit the way with a glowing squid.
2.The villain called up a giant wave, then lit the way with a glowing squid.
3.The villain steered the ocean currents, then hitched a ride on a sea turtle.
4.The villain steered the ocean currents, then lit the way with a glowing squid.
5.The villain flashed a blinding glow, then hitched a ride on a sea turtle.
6.The villain steered the ocean currents, then whistled for a dolphin pal.
7.The villain sang a dizzying song, then whistled for a dolphin pal.
8.The villain sang a dizzying song, then hitched a ride on a sea turtle.
9.The villain sang a dizzying song, then lit the way with a glowing squid.
10.The villain blasted bubble shields, then whistled for a dolphin pal.
11.The villain called up a giant wave, then whistled for a dolphin pal.
12.The villain steered the ocean currents, then hid inside a hermit crab shell.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Case of the Missing Star Pearl
Culprit: Azure Abyss (Current Control · Hermit Crab · Left Finned · Deep Blue · Sticky Kelp)
- Clue 1 (Rounding): "THE VILLAIN DOES NOT HAVE A GLOWING SQUID"Round 17 to the nearest ten = 20 (T) · Round 7,389 to the nearest thousand = 7000 (E) · Round 7,617 to the nearest thousand = 8000 (L) · Round 899 to the nearest hundred = 900 (D) · Round 1,878 to the nearest thousand = 2000 (U) · Round 581 to the nearest hundred = 600 (N) · Round 755 to the nearest hundred = 800 (I) · Round 83 to the nearest ten = 80 (O) · Round 86 to the nearest ten = 90 (A) · Round 455 to the nearest hundred = 500 (H) · Round 170 to the nearest hundred = 200 (V) · Round 4,538 to the nearest thousand = 5000 (W) · Round 297 to the nearest hundred = 300 (S) · Round 2,517 to the nearest thousand = 3000 (Q) · Round 70 to the nearest ten = 70 (G)
- Clue 2 (Addition): "WITNESSES SAW A LEFT FINNED SWIMMER"216 + 429 = 645 (W) · 551 + 390 = 941 (S) · 151 + 136 = 287 (F) · 92 + 191 = 283 (A) · 230 + 423 = 653 (L) · 322 + 373 = 695 (D) · 387 + 450 = 837 (T) · 314 + 294 = 608 (I) · 120 + 184 = 304 (E) · 316 + 149 = 465 (R) · 317 + 341 = 658 (M) · 270 + 347 = 617 (N)
- Clue 3 (Subtraction): "THE THIEF GOT TANGLED IN STICKY KELP"867 - 212 = 655 (T) · 707 - 191 = 516 (S) · 824 - 39 = 785 (D) · 433 - 173 = 260 (E) · 385 - 21 = 364 (F) · 1001 - 344 = 657 (I) · 1073 - 190 = 883 (O) · 374 - 158 = 216 (Y) · 887 - 107 = 780 (P) · 376 - 246 = 130 (L) · 208 - 21 = 187 (K) · 838 - 226 = 612 (N) · 524 - 355 = 169 (H) · 343 - 59 = 284 (A) · 933 - 159 = 774 (C) · 563 - 343 = 220 (G)
- Clue 4 (Multiplication facts (1-12)): "BLUE SCALES WERE DROPPED NEAR THE SAFE"9 × 12 = 108 (B) · 11 × 3 = 33 (O) · 12 × 10 = 120 (T) · 10 × 4 = 40 (U) · 9 × 10 = 90 (P) · 12 × 12 = 144 (R) · 10 × 8 = 80 (S) · 9 × 6 = 54 (H) · 1 × 6 = 6 (N) · 8 × 1 = 8 (A) · 11 × 9 = 99 (D) · 9 × 9 = 81 (F) · 4 × 1 = 4 (E) · 1 × 11 = 11 (W) · 9 × 7 = 63 (C) · 5 × 7 = 35 (L)
- Clue 5 (Division facts (1-12)): surviving statement (box 12) → Azure Abyss33 ÷ 11 = 3 · 15 ÷ 3 = 5 · 70 ÷ 10 = 7 · 10 ÷ 1 = 10 · 64 ÷ 8 = 8 · 32 ÷ 8 = 4 · 66 ÷ 11 = 6 · 2 ÷ 1 = 2 · 27 ÷ 3 = 9 · 3 ÷ 3 = 1 · 66 ÷ 6 = 11
About this mystery
- Grade level
- Grade 3 math
- Math topics
- Rounding, Addition, Subtraction, Multiplication, Division
- Reading level
- grades 3-4
- Theme
- The Case of the Missing Star Pearl — set in Coral Crest Kingdom
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects