🏴☠️ PiratesGrade 8Reading: grades 5-6ExponentsSquare rootsPythagorean theoremOrder of operationsTwo-step equations
The Mystery of Black Sand Cove
Someone plundered the harbor master's vault and swiped the legendary Golden Astrolabe! Clues were left all across the deck. Solve the math ciphers to unmask the pirate 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 | Primary Weapon | Pirate Gear | Dominant Hand | Headwear Style | Pest Control |
|---|---|---|---|---|---|
| Woodes Rogers | Brass Spyglass | Pocket Compass | Left Handed | Braided Dreadlocks | Bright Sun Glare |
| Francois l Olonnais | Brass Spyglass | Trained Parrot | Left Handed | Braided Dreadlocks | Splash of Sea Water |
| Gentleman Jib | Iron Hook | Pocket Compass | Left Handed | Striped Bandana | Splash of Sea Water |
| Samuel Bellamy | Brass Spyglass | Signal Flare | Left Handed | Braided Dreadlocks | Scurvy Lemon Juice |
| Calico Jack | Flintlock Pistol | Boarding Grapple | Left Handed | Striped Bandana | Scurvy Lemon Juice |
| Scurvy Pete | Curved Cutlass | Trained Parrot | Left Handed | Striped Bandana | Splash of Sea Water |
| Ching Shih | Curved Cutlass | Signal Flare | Right Handed | Trikorn Hat | Splash of Sea Water |
| John Rackham | Flintlock Pistol | Boarding Grapple | Right Handed | Trikorn Hat | Scurvy Lemon Juice |
| Stede Bonnet | Curved Cutlass | Boarding Grapple | Left Handed | Striped Bandana | Splash of Sea Water |
| Thomas Tew | Curved Cutlass | Trained Parrot | Right Handed | Trikorn Hat | Bright Sun Glare |
| Sadie the Goat | Brass Spyglass | Trained Parrot | Left Handed | Braided Dreadlocks | Scurvy Lemon Juice |
| Mary Read | Curved Cutlass | Smoke Bomb | Right Handed | Braided Dreadlocks | Scurvy Lemon Juice |
| Howell Davis | Wooden Pegleg | Boarding Grapple | Right Handed | Braided Dreadlocks | Bright Sun Glare |
| Edward England | Wooden Pegleg | Smoke Bomb | Right Handed | Striped Bandana | Splash of Sea Water |
| Blackbeard | Wooden Pegleg | Signal Flare | Right Handed | Braided Dreadlocks | Splash of Sea Water |
| Jean Lafitte | Curved Cutlass | Signal Flare | Left Handed | Striped Bandana | Splash of Sea Water |
| Charles Vane | Curved Cutlass | Trained Parrot | Right Handed | Braided Dreadlocks | Bright Sun Glare |
| Anne Bonny | Curved Cutlass | Trained Parrot | Left Handed | Braided Dreadlocks | Scurvy Lemon Juice |
| Grace O Malley | Iron Hook | Smoke Bomb | Left Handed | Striped Bandana | Splash of Sea Water |
| Cheung Po Tsai | Brass Spyglass | Signal Flare | Right Handed | Trikorn Hat | Bright Sun Glare |
| Barnaby Finch | Flintlock Pistol | Smoke Bomb | Right Handed | Braided Dreadlocks | Bright Sun Glare |
Clue 1
Exponents
A mysterious scroll uses powers of two to encode the secret coordinates of the pirate hideout.
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
64
121
225
324
27
361
361
400
27
729
4
25
225
196
729
25
T
64
128
196
225
400
169
25
100
343
225
T
64
100
25
512
169
400
196
196
4^3 =T
2^2 =D
10^2 =C
11^2 =H
5^2 =O
15^2 =E
19^2 =L
2^7 =U
3^6 =N
3^3 =I
13^2 =P
14^2 =S
20^2 =A
2^9 =M
7^3 =K
18^2 =V
0/16 letters found
Clue 2
Square roots
The quartermaster measures the area of a square treasure chest to figure out the length of its side.
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
25
17
7
14
7
18
T
25
17
15
23
2
7
2
24
4
6
15
T
25
7
10
6
15
19
19
7
2
T
25
17
7
13
17
7
7
14
sqrt(625) =T
sqrt(576) =P
sqrt(324) =F
sqrt(225) =A
sqrt(361) =B
sqrt(529) =N
sqrt(16) =I
sqrt(36) =R
sqrt(100) =G
sqrt(4) =D
sqrt(169) =W
sqrt(196) =L
sqrt(289) =H
sqrt(49) =E
0/14 letters found
Clue 3
Pythagorean theorem
To cross the stormy reef safely, the navigator calculates the straight diagonal distance between two points.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
S
10
5
74
50
S
10
26
82
29
S
10
15
50
87
50
75
15
51
S
10
75
82
5
S
10
75
26
15
20
39
82
74
68
legs 6 and 8, hypotenuse =S
legs 3 and 4, hypotenuse =P
legs 12 and 16, hypotenuse =M
legs 32 and 60, hypotenuse =D
legs 9 and 12, hypotenuse =E
legs 10 and 24, hypotenuse =H
legs 60 and 63, hypotenuse =W
legs 15 and 36, hypotenuse =C
legs 20 and 21, hypotenuse =F
legs 14 and 48, hypotenuse =A
legs 18 and 80, hypotenuse =O
legs 21 and 72, hypotenuse =T
legs 24 and 70, hypotenuse =L
legs 24 and 45, hypotenuse =R
0/14 letters found
Clue 4
Order of operations
A locked cipher box requires solving math operations in the correct order to release the latch.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
S
67
119
110
15
114
70
47
73
56
53
47
56
53
56
20
56
S
67
119
10
110
53
10
53
56
53
56
15
80
11 + 8 × 7 =S
12 × 4 - 28 =W
7 + 2 × 4 =I
10 × 6 - 4 =A
2 + 2 × 4 =O
55 + 2 × 9 =B
38 + 4 × 8 =E
95 + 4 × 6 =T
6 × 10 - 7 =N
12 × 10 - 6 =P
6 × 9 - 7 =D
12 × 10 - 10 =R
8 × 12 - 16 =L
0/13 letters found
Clue 5
Two-step equations — the last clue
Balancing the gold doubloons on the deck scale requires solving for the missing iron weight.
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
3x + 12 = 18, x = ?
6x + 9 = 75, x = ?
3x + 4 = 19, x = ?
2x + 11 = 31, x = ?
6x + 5 = 11, x = ?
2x + 3 = 17, x = ?
4x + 10 = 42, x = ?
5x + 4 = 24, x = ?
5x + 9 = 39, x = ?
4x + 2 = 38, x = ?
4x + 8 = 20, x = ?
Step 2 — cross out the sentence with each answer
1.The villain stumps along on a wooden pegleg, then consults a pocket compass.
2.The villain swings a curved cutlass, then launches a boarding grapple.
3.The villain scratches with an iron hook, then launches a boarding grapple.
4.The villain swings a curved cutlass, then consults a pocket compass.
5.The villain scratches with an iron hook, then drops a heavy smoke bomb.
6.The villain scratches with an iron hook, then signals a trained parrot.
7.The villain brandishes a flintlock pistol, then consults a pocket compass.
8.The villain brandishes a flintlock pistol, then launches a boarding grapple.
9.The villain peers through a brass spyglass, then drops a heavy smoke bomb.
10.The villain brandishes a flintlock pistol, then drops a heavy smoke bomb.
11.The villain swings a curved cutlass, then ignites a bright signal flare.
12.The villain swings a curved cutlass, then signals a trained parrot.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Mystery of Black Sand Cove
Culprit: Scurvy Pete (Curved Cutlass · Trained Parrot · Left Handed · Striped Bandana · Splash of Sea Water)
- Clue 1 (Exponents): "THE VILLAIN DOES NOT USE A POCKET COMPASS"4^3 = 64 (T) · 2^2 = 4 (D) · 10^2 = 100 (C) · 11^2 = 121 (H) · 5^2 = 25 (O) · 15^2 = 225 (E) · 19^2 = 361 (L) · 2^7 = 128 (U) · 3^6 = 729 (N) · 3^3 = 27 (I) · 13^2 = 169 (P) · 14^2 = 196 (S) · 20^2 = 400 (A) · 2^9 = 512 (M) · 7^3 = 343 (K) · 18^2 = 324 (V)
- Clue 2 (Square roots): "THE LEFT HANDED PIRATE GRABBED THE WHEEL"sqrt(625) = 25 (T) · sqrt(576) = 24 (P) · sqrt(324) = 18 (F) · sqrt(225) = 15 (A) · sqrt(361) = 19 (B) · sqrt(529) = 23 (N) · sqrt(16) = 4 (I) · sqrt(36) = 6 (R) · sqrt(100) = 10 (G) · sqrt(4) = 2 (D) · sqrt(169) = 13 (W) · sqrt(196) = 14 (L) · sqrt(289) = 17 (H) · sqrt(49) = 7 (E)
- Clue 3 (Pythagorean theorem): "SPLASH OF SEA WATER STOPS THEM COLD"legs 6 and 8, hypotenuse = 10 (S) · legs 3 and 4, hypotenuse = 5 (P) · legs 12 and 16, hypotenuse = 20 (M) · legs 32 and 60, hypotenuse = 68 (D) · legs 9 and 12, hypotenuse = 15 (E) · legs 10 and 24, hypotenuse = 26 (H) · legs 60 and 63, hypotenuse = 87 (W) · legs 15 and 36, hypotenuse = 39 (C) · legs 20 and 21, hypotenuse = 29 (F) · legs 14 and 48, hypotenuse = 50 (A) · legs 18 and 80, hypotenuse = 82 (O) · legs 21 and 72, hypotenuse = 75 (T) · legs 24 and 70, hypotenuse = 74 (L) · legs 24 and 45, hypotenuse = 51 (R)
- Clue 4 (Order of operations): "STRIPED BANDANA WAS TORN ON A NAIL"11 + 8 × 7 = 67 (S) · 12 × 4 - 28 = 20 (W) · 7 + 2 × 4 = 15 (I) · 10 × 6 - 4 = 56 (A) · 2 + 2 × 4 = 10 (O) · 55 + 2 × 9 = 73 (B) · 38 + 4 × 8 = 70 (E) · 95 + 4 × 6 = 119 (T) · 6 × 10 - 7 = 53 (N) · 12 × 10 - 6 = 114 (P) · 6 × 9 - 7 = 47 (D) · 12 × 10 - 10 = 110 (R) · 8 × 12 - 16 = 80 (L)
- Clue 5 (Two-step equations): surviving statement (box 12) → Scurvy Pete3x + 12 = 18, x = 2 · 6x + 9 = 75, x = 11 · 3x + 4 = 19, x = 5 · 2x + 11 = 31, x = 10 · 6x + 5 = 11, x = 1 · 2x + 3 = 17, x = 7 · 4x + 10 = 42, x = 8 · 5x + 4 = 24, x = 4 · 5x + 9 = 39, x = 6 · 4x + 2 = 38, x = 9 · 4x + 8 = 20, x = 3
About this mystery
- Grade level
- Grade 8 math
- Math topics
- Exponents, Square roots, Pythagorean theorem, Order of operations, Two-step equations
- Reading level
- grades 5-6
- Theme
- The Mystery of Black Sand Cove — set in Black Sand Cove aboard the flagship Sea Serpent
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects