🌊 MermaidsGrade 6Reading: grades 5-6Place valueAdditionMultiplicationRoundingMissing addends
The Mystery of the Missing Royal Pearl
A sneaky mermaid swiped the Glowing Royal Pearl right out of the underwater vault! Help Captain Shellfinder solve math clues to unmask the villain before they escape into the deep trench.
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 | Swim Style | Sea Gadget | Fin Band Side | Tail Scale Color | Pearl Allergy |
|---|---|---|---|---|---|
| Ray Current | Dolphin Kick | Shell Compass | Left Fin Band | Aquamarine | Sea Lavender |
| Marina Wave | Deep Trench Dive | Shell Compass | Right Fin Band | Sunbeam Gold | Sea Lavender |
| Ursula Abyss | Dolphin Kick | Coral Whistle | Right Fin Band | Emerald Green | Sea Lavender |
| Captain Triton | Dolphin Kick | Coral Whistle | Left Fin Band | Aquamarine | Electric Anemone |
| Oceanus Drake | Dolphin Kick | Sea Glass Mirror | Left Fin Band | Aquamarine | Starlight Jelly |
| Wade Waters | Tidal Dash | Coral Whistle | Left Fin Band | Emerald Green | Electric Anemone |
| Coralina Deep | Tidal Dash | Sea Glass Mirror | Right Fin Band | Emerald Green | Starlight Jelly |
| Nerida Blue | Deep Trench Dive | Coral Whistle | Left Fin Band | Emerald Green | Starlight Jelly |
| Calypso Ridge | Dolphin Kick | Kelp Lasso | Left Fin Band | Emerald Green | Electric Anemone |
| Caspian Cove | Sidewinder Glide | Bubble Shield | Left Fin Band | Emerald Green | Sea Lavender |
| Coral Reef | Sidewinder Glide | Kelp Lasso | Left Fin Band | Sunbeam Gold | Sea Lavender |
| Pearlina Glide | Tidal Dash | Shell Compass | Right Fin Band | Sunbeam Gold | Sea Lavender |
| Delphine Splash | Tidal Dash | Kelp Lasso | Left Fin Band | Aquamarine | Starlight Jelly |
| Mako Ridge | Deep Trench Dive | Shell Compass | Left Fin Band | Aquamarine | Starlight Jelly |
| Seabert Fin | Current Surfing | Coral Whistle | Left Fin Band | Aquamarine | Sea Lavender |
| Finneas Tide | Deep Trench Dive | Coral Whistle | Left Fin Band | Aquamarine | Starlight Jelly |
| Bubbles Lagoon | Dolphin Kick | Coral Whistle | Right Fin Band | Aquamarine | Starlight Jelly |
| Triton Vance | Tidal Dash | Coral Whistle | Left Fin Band | Aquamarine | Sea Lavender |
| Shelly Sands | Sidewinder Glide | Bubble Shield | Left Fin Band | Aquamarine | Starlight Jelly |
| Pearl Starling | Dolphin Kick | Kelp Lasso | Left Fin Band | Aquamarine | Electric Anemone |
| Sandy Shoals | Sidewinder Glide | Kelp Lasso | Left Fin Band | Aquamarine | Sea Lavender |
Clue 1
Place value
To decode the first message, analyze the digit values on the palace sonar display.
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
200
4000
600
5000
9000
800
800
30
9000
8000
90
100
600
1000
8000
100
T
200
10
1000
600
30
1000
4000
600
800
800
80
100
6000
500
30
1000
1000
What is the value of the 2 in 39,269?T
What is the value of the 5 in 22,526?P
What is the value of the 1 in 639,215?U
What is the value of the 8 in 44,829?L
What is the value of the 9 in 49,217?I
What is the value of the 6 in 936,140?M
What is the value of the 6 in 357,670?E
What is the value of the 8 in 226,985?C
What is the value of the 1 in 391,567?S
What is the value of the 4 in 324,317?H
What is the value of the 8 in 778,119?N
What is the value of the 3 in 440,138?A
What is the value of the 5 in 435,294?V
What is the value of the 9 in 500,695?D
What is the value of the 1 in 899,142?O
0/15 letters found
Clue 2
Addition
To discover the second hint, combine the counts of sea crystals collected from each reef sector.
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
5217
3361
6221
7384
6264
T
5217
6591
6221
2529
2529
2529
5124
7384
5124
3773
5124
6591
3556
4881
6591
T
5217
3361
6221
4428
6221
4493
T
5217
4493
6264
6591
3216 + 2001 =T
2886 + 3705 =N
2472 + 4912 =W
1992 + 1369 =H
4010 + 2254 =I
1661 + 868 =S
2237 + 2191 =L
3688 + 2533 =E
1702 + 2791 =F
1830 + 3051 =O
1992 + 1564 =D
1662 + 2111 =B
3515 + 1609 =A
0/13 letters found
Clue 3
Multiplication facts (1-12)
To reveal the third clue, calculate the total scales in these equal rows of kelp armors.
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
42
35
36
T
42
35
100
36
4
12
14
8
44
36
6
36
56
56
36
81
25
48
8
T
42
14
44
56
100
9
35
T
42
32
36
56
56
48
6 × 7 =T
5 × 5 =B
4 × 11 =R
2 × 4 =S
2 × 6 =W
2 × 2 =F
10 × 10 =I
2 × 3 =P
4 × 8 =J
9 × 9 =D
9 × 1 =G
8 × 6 =Y
7 × 2 =A
8 × 7 =L
9 × 4 =E
7 × 5 =H
0/16 letters found
Clue 4
Rounding
To unlock the fourth piece of evidence, round the long distance depth gauge readings to the nearest hundred.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
A
50
3700
500
200
30
7000
5000
A
50
700
3000
A
50
130
A
50
500
200
1700
110
1100
20
A
50
900
110
1300
A
50
1100
2300
70
3000
1700
300
1700
110
A
50
500
3700
2900
Round 54 to the nearest tenA
Round 254 to the nearest hundredD
Round 3,722 to the nearest hundredB
Round 1,133 to the nearest hundredS
Round 131 to the nearest tenM
Round 7,017 to the nearest thousandH
Round 2,321 to the nearest hundredF
Round 33 to the nearest tenG
Round 708 to the nearest hundredQ
Round 1,670 to the nearest hundredN
Round 940 to the nearest hundredL
Round 21 to the nearest tenC
Round 1,345 to the nearest hundredW
Round 5,116 to the nearest thousandT
Round 2,853 to the nearest hundredY
Round 111 to the nearest tenE
Round 156 to the nearest hundredI
Round 73 to the nearest tenO
Round 3,134 to the nearest thousandU
Round 525 to the nearest hundredR
0/20 letters found
Clue 5
Missing addends — the last clue
To uncover the final clue, solve for the missing pearl weights needed to balance the vault scale.
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
29 + ___ = 41
20 + ___ = 29
38 + ___ = 44
7 + ___ = 17
28 + ___ = 31
26 + ___ = 28
18 + ___ = 25
4 + ___ = 15
37 + ___ = 45
17 + ___ = 22
32 + ___ = 33
Step 2 — cross out the sentence with each answer
1.The villain darted past in a tidal dash, then flashed a sea glass mirror.
2.The villain glided in with a dolphin kick, then deployed a bubble shield.
3.The villain zipped through with a sidewinder glide, then tangled the guards with a kelp lasso.
4.The villain glided in with a dolphin kick, then flashed a sea glass mirror.
5.The villain zipped through with a sidewinder glide, then checked a shell compass.
6.The villain plunged down in a deep trench dive, then sounded a coral whistle.
7.The villain darted past in a tidal dash, then deployed a bubble shield.
8.The villain darted past in a tidal dash, then checked a shell compass.
9.The villain zipped through with a sidewinder glide, then deployed a bubble shield.
10.The villain zoomed along by current surfing, then tangled the guards with a kelp lasso.
11.The villain zoomed along by current surfing, then sounded a coral whistle.
12.The villain darted past in a tidal dash, then tangled the guards with a kelp lasso.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Mystery of the Missing Royal Pearl
Culprit: Oceanus Drake (Dolphin Kick · Sea Glass Mirror · Left Fin Band · Aquamarine · Starlight Jelly)
- Clue 1 (Place value): "THE VILLAIN DOES NOT USE A SHELL COMPASS"What is the value of the 2 in 39,269? = 200 (T) · What is the value of the 5 in 22,526? = 500 (P) · What is the value of the 1 in 639,215? = 10 (U) · What is the value of the 8 in 44,829? = 800 (L) · What is the value of the 9 in 49,217? = 9000 (I) · What is the value of the 6 in 936,140? = 6000 (M) · What is the value of the 6 in 357,670? = 600 (E) · What is the value of the 8 in 226,985? = 80 (C) · What is the value of the 1 in 391,567? = 1000 (S) · What is the value of the 4 in 324,317? = 4000 (H) · What is the value of the 8 in 778,119? = 8000 (N) · What is the value of the 3 in 440,138? = 30 (A) · What is the value of the 5 in 435,294? = 5000 (V) · What is the value of the 9 in 500,695? = 90 (D) · What is the value of the 1 in 899,142? = 100 (O)
- Clue 2 (Addition): "THE WITNESS SAW A BAND ON THE LEFT FIN"3216 + 2001 = 5217 (T) · 2886 + 3705 = 6591 (N) · 2472 + 4912 = 7384 (W) · 1992 + 1369 = 3361 (H) · 4010 + 2254 = 6264 (I) · 1661 + 868 = 2529 (S) · 2237 + 2191 = 4428 (L) · 3688 + 2533 = 6221 (E) · 1702 + 2791 = 4493 (F) · 1830 + 3051 = 4881 (O) · 1992 + 1564 = 3556 (D) · 1662 + 2111 = 3773 (B) · 3515 + 1609 = 5124 (A)
- Clue 3 (Multiplication facts (1-12)): "THE THIEF WAS REPELLED BY STARLIGHT JELLY"6 × 7 = 42 (T) · 5 × 5 = 25 (B) · 4 × 11 = 44 (R) · 2 × 4 = 8 (S) · 2 × 6 = 12 (W) · 2 × 2 = 4 (F) · 10 × 10 = 100 (I) · 2 × 3 = 6 (P) · 4 × 8 = 32 (J) · 9 × 9 = 81 (D) · 9 × 1 = 9 (G) · 8 × 6 = 48 (Y) · 7 × 2 = 14 (A) · 8 × 7 = 56 (L) · 9 × 4 = 36 (E) · 7 × 5 = 35 (H)
- Clue 4 (Rounding): "A BRIGHT AQUAMARINE SCALE WAS FOUND NEARBY"Round 54 to the nearest ten = 50 (A) · Round 254 to the nearest hundred = 300 (D) · Round 3,722 to the nearest hundred = 3700 (B) · Round 1,133 to the nearest hundred = 1100 (S) · Round 131 to the nearest ten = 130 (M) · Round 7,017 to the nearest thousand = 7000 (H) · Round 2,321 to the nearest hundred = 2300 (F) · Round 33 to the nearest ten = 30 (G) · Round 708 to the nearest hundred = 700 (Q) · Round 1,670 to the nearest hundred = 1700 (N) · Round 940 to the nearest hundred = 900 (L) · Round 21 to the nearest ten = 20 (C) · Round 1,345 to the nearest hundred = 1300 (W) · Round 5,116 to the nearest thousand = 5000 (T) · Round 2,853 to the nearest hundred = 2900 (Y) · Round 111 to the nearest ten = 110 (E) · Round 156 to the nearest hundred = 200 (I) · Round 73 to the nearest ten = 70 (O) · Round 3,134 to the nearest thousand = 3000 (U) · Round 525 to the nearest hundred = 500 (R)
- Clue 5 (Missing addends): surviving statement (box 4) → Oceanus Drake29 + ___ = 41 = 12 · 20 + ___ = 29 = 9 · 38 + ___ = 44 = 6 · 7 + ___ = 17 = 10 · 28 + ___ = 31 = 3 · 26 + ___ = 28 = 2 · 18 + ___ = 25 = 7 · 4 + ___ = 15 = 11 · 37 + ___ = 45 = 8 · 17 + ___ = 22 = 5 · 32 + ___ = 33 = 1
About this mystery
- Grade level
- Grade 6 math
- Math topics
- Place value, Addition, Multiplication, Rounding, Missing addends
- Reading level
- grades 5-6
- Theme
- The Mystery of the Missing Royal Pearl — set in The Coral Reef Palace
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects