Grade 4Reading: grades 3-4AdditionRoundingSubtractionMultiplicationDivision

The Mystery of the Sunken Compass

Someone swiped the ancient Golden Compass right out of Captain Barnaby map tent! Follow the clues around Starfish Cove to unmask the thief before they set sail.

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	Main Gadget	Escape Vehicle	Handedness	Bandana Color	Soggy Fear
Wave Winslow	Hook Launcher	Speed Rowboat	Right Handed	Blue Bandana	Sticky Honey
Pebble Pete	Metal Detector	Wooden Raft	Right Handed	Red Bandana	Sticky Honey
Marina Finch	Smoke Bomb	Wooden Raft	Left Handed	Blue Bandana	Loud Whistles
Captain Coral	Pocket Telescope	Speed Rowboat	Right Handed	Red Bandana	Bright Flares
Breeze Bailey	Smoke Bomb	Speed Rowboat	Left Handed	Red Bandana	Loud Whistles
Clipper West	Smoke Bomb	Wooden Raft	Left Handed	Blue Bandana	Bright Flares
Salty Sam	Smoke Bomb	Zipline Harness	Right Handed	Blue Bandana	Bright Flares
Fisher Frank	Grappling Rope	Wooden Raft	Left Handed	Blue Bandana	Bright Flares
Anchor Andy	Hook Launcher	Wooden Raft	Left Handed	Blue Bandana	Sticky Honey
Rudder Ruth	Hook Launcher	Speed Rowboat	Left Handed	Blue Bandana	Bright Flares
Beacon Bob	Pocket Telescope	Wooden Raft	Right Handed	Gold Bandana	Loud Whistles
Reef Riley	Pocket Telescope	Zipline Harness	Left Handed	Red Bandana	Loud Whistles
Piper Plum	Pocket Telescope	Flying Glider	Left Handed	Blue Bandana	Bright Flares
Cobalt Cole	Grappling Rope	Speed Rowboat	Left Handed	Blue Bandana	Sticky Honey
Harbor Holly	Pocket Telescope	Wooden Raft	Left Handed	Red Bandana	Bright Flares
Barnaby Blake	Metal Detector	Flying Glider	Right Handed	Blue Bandana	Sticky Honey
Gulliver Glen	Pocket Telescope	Zipline Harness	Right Handed	Blue Bandana	Loud Whistles
Sandy Shore	Hook Launcher	Coconut Cart	Left Handed	Blue Bandana	Bright Flares
Tide Trevor	Grappling Rope	Coconut Cart	Left Handed	Gold Bandana	Sticky Honey
Shellie Shark	Pocket Telescope	Wooden Raft	Right Handed	Red Bandana	Bright Flares
Jolly Jasper	Pocket Telescope	Speed Rowboat	Right Handed	Blue Bandana	Loud Whistles

Clue 1

Addition

You tally up all the brass doubloons left near the map table to see where the suspect stepped.

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

5412

3126

7213

4289

5806

9276

7359

5806

5629

9252

5806

9252

5629

7815

5412

5627

8545

7213

7359

7356

9276

2405

5806

5629

2558

9276

5806

9252

7213

2753

2573 + 2839 =T

979 + 1774 =R

832 + 1573 =Y

3188 + 2439 =U

2630 + 2999 =N

5900 + 3376 =L

3318 + 4497 =O

1276 + 1282 =G

2659 + 5886 =S

4405 + 2954 =A

5470 + 3782 =D

2074 + 3732 =I

4588 + 2625 =E

1402 + 2887 =V

3739 + 3617 =F

1677 + 1449 =H

0/16 letters found

Clue 2

Rounding

The lookout tower radar rounds the island distances to the nearest ten yards to track the escape route.

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

230

200

300

4300

2900

230

290

4300

300

1700

1300

4300

1300

2900

700

5000

900

1300

3000

4300

290

Round 27 to the nearest tenA

Round 2,925 to the nearest hundredS

Round 17 to the nearest tenF

Round 4,877 to the nearest thousandO

Round 343 to the nearest hundredT

Round 685 to the nearest hundredC

Round 868 to the nearest hundredU

Round 73 to the nearest tenN

Round 1,708 to the nearest hundredH

Round 4,288 to the nearest hundredE

Round 286 to the nearest tenL

Round 233 to the nearest tenW

Round 1,267 to the nearest hundredD

Round 159 to the nearest hundredI

Round 3,225 to the nearest thousandR

0/15 letters found

Clue 3

Subtraction

You compare the total supplies in the storage chest before and after the robbery to find missing gear.

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

1183

8038

6910

2820

5113

1289

3372

7134

8469

8038

6151

7058

2542

8469

8038

6151

4393

1289

5113

6151

8379

6910

7134

8469

6910

2073

8469

4982

8469

3076

5026 - 3843 =B

7333 - 4257 =Y

8999 - 4606 =D

11184 - 3146 =R

9350 - 2216 =L

8724 - 2573 =E

10702 - 3644 =S

11251 - 2872 =V

4739 - 2666 =N

4985 - 3696 =T

5608 - 495 =H

3290 - 470 =G

5235 - 2693 =C

12780 - 4311 =A

6913 - 3 =I

8659 - 3677 =W

4831 - 1459 =F

0/17 letters found

Clue 4

Multiplication facts (1-12)

You count equal stacks of tropical fruit crates lined up in rows near the dock.

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

100

9 × 9 =T

3 × 10 =N

7 × 7 =R

1 × 1 =U

5 × 10 =S

12 × 3 =E

10 × 10 =A

10 × 8 =L

8 × 11 =C

1 × 5 =B

3 × 5 =H

7 × 11 =O

12 × 7 =D

9 × 3 =P

0/14 letters found

Clue 5

Division facts (1-12) — the last clue

You split the island rescue rations equally among the search teams heading into the jungle.

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

10 ÷ 1 = ?

7 ÷ 7 = ?

60 ÷ 12 = ?

35 ÷ 5 = ?

45 ÷ 5 = ?

12 ÷ 1 = ?

20 ÷ 5 = ?

44 ÷ 4 = ?

66 ÷ 11 = ?

24 ÷ 12 = ?

18 ÷ 6 = ?

Step 2 — cross out the sentence with each answer

1.The villain used a hook launcher, then paddled a speed rowboat.

2.The villain swung on a grappling rope, then zipped away on a zipline harness.

3.The villain spied through a pocket telescope, then rolled off in a coconut cart.

4.The villain threw a smoke bomb, then rolled off in a coconut cart.

5.The villain threw a smoke bomb, then escaped on a wooden raft.

6.The villain scanned with a metal detector, then zipped away on a zipline harness.

7.The villain scanned with a metal detector, then soared off on a flying glider.

8.The villain swung on a grappling rope, then escaped on a wooden raft.

9.The villain swung on a grappling rope, then rolled off in a coconut cart.

10.The villain used a hook launcher, then rolled off in a coconut cart.

11.The villain spied through a pocket telescope, then escaped on a wooden raft.

12.The villain spied through a pocket telescope, then zipped away on a zipline harness.

Solve it

Name the culprit

Choose the one suspect left standing.

Answer Key — The Mystery of the Sunken Compass

Culprit: Fisher Frank (Grappling Rope · Wooden Raft · Left Handed · Blue Bandana · Bright Flares)

Clue 1 (Addition): "THE VILLAIN DID NOT USE A FLYING GLIDER"
2573 + 2839 = 5412 (T) · 979 + 1774 = 2753 (R) · 832 + 1573 = 2405 (Y) · 3188 + 2439 = 5627 (U) · 2630 + 2999 = 5629 (N) · 5900 + 3376 = 9276 (L) · 3318 + 4497 = 7815 (O) · 1276 + 1282 = 2558 (G) · 2659 + 5886 = 8545 (S) · 4405 + 2954 = 7359 (A) · 5470 + 3782 = 9252 (D) · 2074 + 3732 = 5806 (I) · 4588 + 2625 = 7213 (E) · 1402 + 2887 = 4289 (V) · 3739 + 3617 = 7356 (F) · 1677 + 1449 = 3126 (H)
Clue 2 (Rounding): "A WITNESS SAW A LEFT HANDED SCOUNDREL"
Round 27 to the nearest ten = 30 (A) · Round 2,925 to the nearest hundred = 2900 (S) · Round 17 to the nearest ten = 20 (F) · Round 4,877 to the nearest thousand = 5000 (O) · Round 343 to the nearest hundred = 300 (T) · Round 685 to the nearest hundred = 700 (C) · Round 868 to the nearest hundred = 900 (U) · Round 73 to the nearest ten = 70 (N) · Round 1,708 to the nearest hundred = 1700 (H) · Round 4,288 to the nearest hundred = 4300 (E) · Round 286 to the nearest ten = 290 (L) · Round 233 to the nearest ten = 230 (W) · Round 1,267 to the nearest hundred = 1300 (D) · Round 159 to the nearest hundred = 200 (I) · Round 3,225 to the nearest thousand = 3000 (R)
Clue 3 (Subtraction): "BRIGHT FLARES SCARED THE VILLAIN AWAY"
5026 - 3843 = 1183 (B) · 7333 - 4257 = 3076 (Y) · 8999 - 4606 = 4393 (D) · 11184 - 3146 = 8038 (R) · 9350 - 2216 = 7134 (L) · 8724 - 2573 = 6151 (E) · 10702 - 3644 = 7058 (S) · 11251 - 2872 = 8379 (V) · 4739 - 2666 = 2073 (N) · 4985 - 3696 = 1289 (T) · 5608 - 495 = 5113 (H) · 3290 - 470 = 2820 (G) · 5235 - 2693 = 2542 (C) · 12780 - 4311 = 8469 (A) · 6913 - 3 = 6910 (I) · 8659 - 3677 = 4982 (W) · 4831 - 1459 = 3372 (F)
Clue 4 (Multiplication facts (1-12)): "THE SCOUNDREL DROPPED A BLUE BANDANA"
9 × 9 = 81 (T) · 3 × 10 = 30 (N) · 7 × 7 = 49 (R) · 1 × 1 = 1 (U) · 5 × 10 = 50 (S) · 12 × 3 = 36 (E) · 10 × 10 = 100 (A) · 10 × 8 = 80 (L) · 8 × 11 = 88 (C) · 1 × 5 = 5 (B) · 3 × 5 = 15 (H) · 7 × 11 = 77 (O) · 12 × 7 = 84 (D) · 9 × 3 = 27 (P)
Clue 5 (Division facts (1-12)): surviving statement (box 8) → Fisher Frank
10 ÷ 1 = 10 · 7 ÷ 7 = 1 · 60 ÷ 12 = 5 · 35 ÷ 5 = 7 · 45 ÷ 5 = 9 · 12 ÷ 1 = 12 · 20 ÷ 5 = 4 · 44 ÷ 4 = 11 · 66 ÷ 11 = 6 · 24 ÷ 12 = 2 · 18 ÷ 6 = 3

About this mystery

Grade level: Grade 4 math
Math topics: Addition, Rounding, Subtraction, Multiplication, Division
Reading level: grades 3-4
Theme: The Mystery of the Sunken Compass — set in Starfish Cove Pirate Camp
Format: Interactive online & printable worksheet with answer key
Solution: One unique, verified culprit among 21 suspects

More free printable math cases

4th grade worksheets Addition worksheets Subtraction worksheets Multiplication worksheets Division worksheets Rounding worksheets All worksheets →

The Great Championship Trophy Mystery

Grade 4

The Case of the Missing Star Crystal

Grade 4

The Mystery of the Rogue Bot

Grade 4

The Case of the Missing Diamond Trophy

Grade 4