Grade 4Reading: grades 3-4AdditionRoundingSubtractionMultiplicationDivision

The Sunken Compass Mystery

A sneaky island bandit swiped the golden sun compass right out of the camp tent! The expedition squad needs your math skills to crack the hidden clues and catch the culprit.

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	Travel Gear	Pocket Tool	Dominant Hand	Headwear	Distraction Trap
Seeker Lily	JUNGLE STILTS	SIGNAL HORN	LEFT HANDED	GOLDEN CAP	LOUD BELL
Pioneer Owen	GRAPPLING HOOK	TREASURE MAP	RIGHT HANDED	BLUE BANDANA	CITRUS SPRAY
Ranger Leo	JUNGLE STILTS	ROPE LADDER	LEFT HANDED	BLUE BANDANA	CITRUS SPRAY
Coastguard Noah	JUNGLE STILTS	SMOKE FLARE	LEFT HANDED	BLUE BANDANA	LOUD BELL
Rover Zoe	SAND SKIMMER	ROPE LADDER	RIGHT HANDED	BLUE BANDANA	LOUD BELL
Skywatcher Liam	GLIDER WINGS	TREASURE MAP	LEFT HANDED	GREEN HELMET	BRIGHT LIGHT
Voyager Ella	GRAPPLING HOOK	TREASURE MAP	RIGHT HANDED	BLUE BANDANA	BRIGHT LIGHT
Caver Mia	GLIDER WINGS	POCKET COMPASS	RIGHT HANDED	BLUE BANDANA	CITRUS SPRAY
Diver Ethan	SAND SKIMMER	POCKET COMPASS	LEFT HANDED	BLUE BANDANA	CITRUS SPRAY
Navigator Ben	SAND SKIMMER	TREASURE MAP	RIGHT HANDED	GOLDEN CAP	BRIGHT LIGHT
Captain Avery	JUNGLE STILTS	TREASURE MAP	LEFT HANDED	BLUE BANDANA	CITRUS SPRAY
Guide Mason	GLIDER WINGS	ROPE LADDER	RIGHT HANDED	GREEN HELMET	LOUD BELL
Trekker Caleb	SAND SKIMMER	TREASURE MAP	RIGHT HANDED	BLUE BANDANA	LOUD BELL
Forager James	SAND SKIMMER	SMOKE FLARE	RIGHT HANDED	BLUE BANDANA	CITRUS SPRAY
Hiker Jack	GLIDER WINGS	ROPE LADDER	RIGHT HANDED	BLUE BANDANA	CITRUS SPRAY
Surveyor Lucas	GRAPPLING HOOK	ROPE LADDER	RIGHT HANDED	GOLDEN CAP	LOUD BELL
Pathfinder Ruby	JUNGLE STILTS	SIGNAL HORN	RIGHT HANDED	GREEN HELMET	BRIGHT LIGHT
Pilot Chloe	GLIDER WINGS	SMOKE FLARE	LEFT HANDED	GOLDEN CAP	CITRUS SPRAY
Sailor Ivy	GRAPPLING HOOK	POCKET COMPASS	RIGHT HANDED	GREEN HELMET	CITRUS SPRAY
Explorer Maya	JUNGLE STILTS	POCKET COMPASS	LEFT HANDED	GREEN HELMET	BRIGHT LIGHT
Outrider Ava	SAND SKIMMER	SIGNAL HORN	RIGHT HANDED	BLUE BANDANA	CITRUS SPRAY

Clue 1

Addition

Ranger Leo counted up the tally marks on the supply crate to reveal the first 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.

7738

2574

9480

4708

4664

2246

2139

4664

9548

5977

6550

9480

5787

9548

6550

7738

5264

2139

6311

4551

2139

5787

6104

6550

8472

9480

3545

2246

2139

6311

9480

3690 + 4048 =T

2821 + 3729 =O

686 + 1560 =L

2258 + 3006 =C

2169 + 3618 =S

2000 + 2551 =Y

2192 + 2472 =I

4015 + 2296 =R

1829 + 4148 =D

4887 + 4661 =N

2964 + 5508 =K

1266 + 1308 =H

1212 + 2333 =F

1367 + 772 =A

2507 + 3597 =M

2971 + 1737 =V

5130 + 4350 =E

0/17 letters found

Clue 2

Rounding

The team checked the dial on the island radar station which rounded the signals to get a clear match.

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

170

2300

4300

200

500

200

1700

230

170

2300

500

2900

5000

290

170

290

3700

290

7000

500

2000

500

200

290

130

200

290

2900

500

Round 169 to the nearest tenR

Round 5,083 to the nearest thousandW

Round 4,294 to the nearest hundredG

Round 23 to the nearest tenP

Round 289 to the nearest tenE

Round 7,122 to the nearest thousandF

Round 2,925 to the nearest hundredS

Round 231 to the nearest hundredH

Round 1,744 to the nearest hundredA

Round 2,421 to the nearest thousandO

Round 88 to the nearest tenN

Round 514 to the nearest hundredT

Round 229 to the nearest tenD

Round 130 to the nearest tenC

Round 3,716 to the nearest hundredL

Round 2,335 to the nearest hundredI

0/16 letters found

Clue 3

Subtraction

Tracker Sam calculated how many coconut canteens were missing from the shed.

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

2138

4346

4457

4967

6147

1888

5339

4967

1081

2454

1888

4457

6482

5339

3766

4508

4457

8025

3766

4508

1081

1888

8025

4346

2007

8524

3651

1081

2007

4508

4346

4457

4216 - 2078 =C

2289 - 401 =S

3366 - 2285 =A

7632 - 2293 =P

7406 - 4952 =Y

11294 - 4812 =O

7815 - 4049 =E

7149 - 2803 =I

9245 - 4788 =T

11145 - 3120 =H

10883 - 4736 =U

6842 - 3191 =B

10134 - 1610 =G

6514 - 2006 =D

4050 - 2043 =N

6795 - 1828 =R

0/16 letters found

Clue 4

Multiplication facts (1-12)

Scout Nora counted the equal rows of rescue flares to unlock the hidden code box.

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

100

121

9 × 12 =S

8 × 4 =D

11 × 9 =R

2 × 7 =A

10 × 2 =W

8 × 10 =O

11 × 2 =N

6 × 7 =F

10 × 10 =M

11 × 11 =E

7 × 8 =T

1 × 10 =L

2 × 8 =U

3 × 5 =B

0/14 letters found

Clue 5

Division facts (1-12) — the last clue

The crew shared the remaining energy bars equally among all five base camps to reveal the final answer.

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

16 ÷ 2 = ?

40 ÷ 10 = ?

72 ÷ 8 = ?

20 ÷ 4 = ?

9 ÷ 9 = ?

60 ÷ 10 = ?

63 ÷ 9 = ?

55 ÷ 5 = ?

120 ÷ 10 = ?

100 ÷ 10 = ?

8 ÷ 4 = ?

Step 2 — cross out the sentence with each answer

1.The villain strided over the mud, then read a pocket compass.

2.The villain dashed across the dunes, then checked a dusty map.

3.The villain dashed across the dunes, then sounded a loud horn.

4.The villain glided over the reef, then read a pocket compass.

5.The villain dived into the lagoon, then sounded a loud horn.

6.The villain glided over the reef, then checked a dusty map.

7.The villain dashed across the dunes, then dropped a bright flare.

8.The villain swung across the canyon, then checked a dusty map.

9.The villain glided over the reef, then unfolded a rope ladder.

10.The villain strided over the mud, then sounded a loud horn.

11.The villain dived into the lagoon, then dropped a bright flare.

12.The villain strided over the mud, then dropped a bright flare.

Solve it

Name the culprit

Choose the one suspect left standing.

Answer Key — The Sunken Compass Mystery

Culprit: Outrider Ava (SAND SKIMMER · SIGNAL HORN · RIGHT HANDED · BLUE BANDANA · CITRUS SPRAY)

Clue 1 (Addition): "THE VILLAIN DOES NOT CARRY A SMOKE FLARE"
3690 + 4048 = 7738 (T) · 2821 + 3729 = 6550 (O) · 686 + 1560 = 2246 (L) · 2258 + 3006 = 5264 (C) · 2169 + 3618 = 5787 (S) · 2000 + 2551 = 4551 (Y) · 2192 + 2472 = 4664 (I) · 4015 + 2296 = 6311 (R) · 1829 + 4148 = 5977 (D) · 4887 + 4661 = 9548 (N) · 2964 + 5508 = 8472 (K) · 1266 + 1308 = 2574 (H) · 1212 + 2333 = 3545 (F) · 1367 + 772 = 2139 (A) · 2507 + 3597 = 6104 (M) · 2971 + 1737 = 4708 (V) · 5130 + 4350 = 9480 (E)
Clue 2 (Rounding): "RIGHT HAND PRINTS WERE LEFT ON THE CHEST"
Round 169 to the nearest ten = 170 (R) · Round 5,083 to the nearest thousand = 5000 (W) · Round 4,294 to the nearest hundred = 4300 (G) · Round 23 to the nearest ten = 20 (P) · Round 289 to the nearest ten = 290 (E) · Round 7,122 to the nearest thousand = 7000 (F) · Round 2,925 to the nearest hundred = 2900 (S) · Round 231 to the nearest hundred = 200 (H) · Round 1,744 to the nearest hundred = 1700 (A) · Round 2,421 to the nearest thousand = 2000 (O) · Round 88 to the nearest ten = 90 (N) · Round 514 to the nearest hundred = 500 (T) · Round 229 to the nearest ten = 230 (D) · Round 130 to the nearest ten = 130 (C) · Round 3,716 to the nearest hundred = 3700 (L) · Round 2,335 to the nearest hundred = 2300 (I)
Clue 3 (Subtraction): "CITRUS SPRAY STOPPED THE DASHING BANDIT"
4216 - 2078 = 2138 (C) · 2289 - 401 = 1888 (S) · 3366 - 2285 = 1081 (A) · 7632 - 2293 = 5339 (P) · 7406 - 4952 = 2454 (Y) · 11294 - 4812 = 6482 (O) · 7815 - 4049 = 3766 (E) · 7149 - 2803 = 4346 (I) · 9245 - 4788 = 4457 (T) · 11145 - 3120 = 8025 (H) · 10883 - 4736 = 6147 (U) · 6842 - 3191 = 3651 (B) · 10134 - 1610 = 8524 (G) · 6514 - 2006 = 4508 (D) · 4050 - 2043 = 2007 (N) · 6795 - 1828 = 4967 (R)
Clue 4 (Multiplication facts (1-12)): "STRANDS FROM A BLUE BANDANA WERE FOUND"
9 × 12 = 108 (S) · 8 × 4 = 32 (D) · 11 × 9 = 99 (R) · 2 × 7 = 14 (A) · 10 × 2 = 20 (W) · 8 × 10 = 80 (O) · 11 × 2 = 22 (N) · 6 × 7 = 42 (F) · 10 × 10 = 100 (M) · 11 × 11 = 121 (E) · 7 × 8 = 56 (T) · 1 × 10 = 10 (L) · 2 × 8 = 16 (U) · 3 × 5 = 15 (B)
Clue 5 (Division facts (1-12)): surviving statement (box 3) → Outrider Ava
16 ÷ 2 = 8 · 40 ÷ 10 = 4 · 72 ÷ 8 = 9 · 20 ÷ 4 = 5 · 9 ÷ 9 = 1 · 60 ÷ 10 = 6 · 63 ÷ 9 = 7 · 55 ÷ 5 = 11 · 120 ÷ 10 = 12 · 100 ÷ 10 = 10 · 8 ÷ 4 = 2

About this mystery

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

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