🤖 Robots, PiratesGrade 2Reading: grades 3-4MultiplicationPlace valueAdditionSubtractionMissing addends
The Mystery of the Golden Gear
Harbor Master Gearbeard woke up to find his shiny Golden Gear missing! A sneaky robot pirate crept onto the dockyard and snatched it before sunrise. Detective Bot must trace the clues and find 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 | Primary Gadget | Cyber Cannon | Stance | Bandana Color | Weakness |
|---|---|---|---|---|---|
| Tracker Tom | Laser Hook | Frost Beam | Right Footed | Black Bandana | Loud Whistles |
| Radar Ray | Magnet Claw | Frost Beam | Left Footed | Red Bandana | Loud Whistles |
| Salty Wires | Drill Arm | Rust Blast | Right Footed | Black Bandana | Soapy Water |
| Copperbeard | Magnet Claw | Rust Blast | Left Footed | Black Bandana | Soapy Water |
| Ollie Oilcan | Rocket Boot | Oil Blaster | Left Footed | Black Bandana | Loud Whistles |
| Rusty Rusty | Drill Arm | Sonic Cannon | Right Footed | Black Bandana | Bright Flashlights |
| Iron Sam | Laser Hook | Frost Beam | Left Footed | Black Bandana | Loud Whistles |
| Patch Byte | Magnet Claw | Oil Blaster | Left Footed | Black Bandana | Loud Whistles |
| Welder Wally | Rocket Boot | Rust Blast | Left Footed | Black Bandana | Loud Whistles |
| Gearhead Greta | Laser Hook | Rust Blast | Right Footed | Black Bandana | Loud Whistles |
| Rivet Rachel | Steam Jet | Sonic Cannon | Left Footed | Black Bandana | Loud Whistles |
| Anchor Amy | Rocket Boot | Spark Cannon | Left Footed | Blue Bandana | Bright Flashlights |
| Mechanic Mae | Laser Hook | Frost Beam | Left Footed | Blue Bandana | Bright Flashlights |
| Barnaby Bolts | Drill Arm | Frost Beam | Left Footed | Black Bandana | Bright Flashlights |
| Scrapjack | Drill Arm | Sonic Cannon | Left Footed | Black Bandana | Loud Whistles |
| Circuit Cy | Magnet Claw | Rust Blast | Right Footed | Blue Bandana | Bright Flashlights |
| Booster Bob | Rocket Boot | Frost Beam | Right Footed | Blue Bandana | Soapy Water |
| Cannon Carl | Drill Arm | Frost Beam | Left Footed | Red Bandana | Loud Whistles |
| Binnacle Ben | Laser Hook | Oil Blaster | Left Footed | Black Bandana | Loud Whistles |
| Captain Sprocket | Laser Hook | Sonic Cannon | Right Footed | Red Bandana | Bright Flashlights |
| Pegleg Piston | Magnet Claw | Rust Blast | Right Footed | Black Bandana | Soapy Water |
Clue 1
Multiplication facts (1-12)
Harbor Master Gearbeard counted crates of spare bolts stacked in equal rows across the deck to find a hidden code.
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
5
33
50
36
20
50
40
90
8
120
12
T
5
2
12
50
36
20
12
T
5
6
36
50
40
20
12
30
45
120
45
40
36
T
5
50
35
1 × 5 =T
12 × 1 =O
2 × 4 =Y
6 × 5 =I
10 × 9 =K
3 × 11 =H
10 × 2 =N
10 × 12 =B
5 × 9 =L
2 × 1 =D
10 × 4 =A
4 × 9 =S
7 × 5 =R
5 × 10 =E
6 × 1 =U
0/15 letters found
Clue 2
Place value
The guard robot checked the digital door log by reading the digits in the tens and ones places.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
F
49
11
11
54
78
97
52
68
54
33
33
26
11
55
54
26
30
87
11
54
52
33
25
30
F
49
54
F
49
11
11
54
30
83
What number has 4 tens and 9 ones?F
What number has 8 tens and 7 ones?B
What number has 5 tens and 5 ones?W
What number has 2 tens and 5 ones?L
What number has 8 tens and 3 ones?D
What number has 3 tens and 0 ones?E
What number has 7 tens and 8 ones?P
What number has 6 tens and 8 ones?N
What number has 2 tens and 6 ones?H
What number has 1 ten and 1 one?O
What number has 5 tens and 2 ones?I
What number has 9 tens and 7 ones?R
What number has 3 tens and 3 ones?S
What number has 5 tens and 4 ones?T
0/14 letters found
Clue 3
Addition
Detective Bot added up all the brass coins found scattered near the dock gate.
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
37
84
27
69
44
68
44
T
37
26
84
83
T
37
58
44
47
96
67
69
44
85
35
44
83
58
47
84
81
26
T
37
35
27
26
18 + 19 =T
24 + 34 =D
9 + 17 =S
30 + 55 =M
46 + 38 =H
11 + 24 =L
27 + 40 =F
36 + 45 =I
30 + 38 =B
27 + 17 =O
46 + 50 =N
38 + 45 =U
29 + 40 =R
15 + 12 =E
26 + 21 =W
0/15 letters found
Clue 4
Subtraction
The crew calculated how many energy cells remained in the ship battery after the break in.
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
25
23
32
82
57
83
48
A
25
26
78
83
A
25
57
19
A
25
57
A
25
20
A
25
27
48
80
86
23
A
25
23
23
22
80
27
26
80
57
80
37 - 12 =A
66 - 9 =N
121 - 35 =F
50 - 2 =L
40 - 21 =D
101 - 18 =B
65 - 33 =O
45 - 18 =S
54 - 34 =W
119 - 39 =E
88 - 6 =R
36 - 14 =H
65 - 39 =C
60 - 37 =T
112 - 34 =K
0/15 letters found
Clue 5
Missing addends — the last clue
Gearbeard needed a full power charge for the searchlight, so he figured out how much energy was missing.
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
4 + ___ = 5
3 + ___ = 14
7 + ___ = 15
9 + ___ = 16
8 + ___ = 10
9 + ___ = 13
3 + ___ = 8
6 + ___ = 18
6 + ___ = 15
10 + ___ = 20
1 + ___ = 7
Step 2 — cross out the sentence with each answer
1.The villain zoomed with a rocket boot, then sprayed a rust blast.
2.The villain grabbed with a magnet claw, then sparked a spark cannon.
3.The villain fired a laser hook, then zapped a frost beam.
4.The villain fired a laser hook, then squirted an oil blaster.
5.The villain fired a laser hook, then shot a sonic cannon.
6.The villain grabbed with a magnet claw, then sprayed a rust blast.
7.The villain zoomed with a rocket boot, then sparked a spark cannon.
8.The villain spun a drill arm, then shot a sonic cannon.
9.The villain blasted a steam jet, then squirted an oil blaster.
10.The villain spun a drill arm, then sprayed a rust blast.
11.The villain blasted a steam jet, then shot a sonic cannon.
12.The villain fired a laser hook, then sprayed a rust blast.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Mystery of the Golden Gear
Culprit: Iron Sam (Laser Hook · Frost Beam · Left Footed · Black Bandana · Loud Whistles)
- Clue 1 (Multiplication facts (1-12)): "THE SNEAKY BOT DOES NOT USE AN OIL BLASTER"1 × 5 = 5 (T) · 12 × 1 = 12 (O) · 2 × 4 = 8 (Y) · 6 × 5 = 30 (I) · 10 × 9 = 90 (K) · 3 × 11 = 33 (H) · 10 × 2 = 20 (N) · 10 × 12 = 120 (B) · 5 × 9 = 45 (L) · 2 × 1 = 2 (D) · 10 × 4 = 40 (A) · 4 × 9 = 36 (S) · 7 × 5 = 35 (R) · 5 × 10 = 50 (E) · 6 × 1 = 6 (U)
- Clue 2 (Place value): "FOOTPRINTS SHOW THE BOT IS LEFT FOOTED"What number has 4 tens and 9 ones? = 49 (F) · What number has 8 tens and 7 ones? = 87 (B) · What number has 5 tens and 5 ones? = 55 (W) · What number has 2 tens and 5 ones? = 25 (L) · What number has 8 tens and 3 ones? = 83 (D) · What number has 3 tens and 0 ones? = 30 (E) · What number has 7 tens and 8 ones? = 78 (P) · What number has 6 tens and 8 ones? = 68 (N) · What number has 2 tens and 6 ones? = 26 (H) · What number has 1 ten and 1 one? = 11 (O) · What number has 5 tens and 2 ones? = 52 (I) · What number has 9 tens and 7 ones? = 97 (R) · What number has 3 tens and 3 ones? = 33 (S) · What number has 5 tens and 4 ones? = 54 (T)
- Clue 3 (Addition): "THE ROBOT SHUT DOWN FROM LOUD WHISTLES"18 + 19 = 37 (T) · 24 + 34 = 58 (D) · 9 + 17 = 26 (S) · 30 + 55 = 85 (M) · 46 + 38 = 84 (H) · 11 + 24 = 35 (L) · 27 + 40 = 67 (F) · 36 + 45 = 81 (I) · 30 + 38 = 68 (B) · 27 + 17 = 44 (O) · 46 + 50 = 96 (N) · 38 + 45 = 83 (U) · 29 + 40 = 69 (R) · 15 + 12 = 27 (E) · 26 + 21 = 47 (W)
- Clue 4 (Subtraction): "A TORN BLACK BANDANA WAS LEFT AT THE SCENE"37 - 12 = 25 (A) · 66 - 9 = 57 (N) · 121 - 35 = 86 (F) · 50 - 2 = 48 (L) · 40 - 21 = 19 (D) · 101 - 18 = 83 (B) · 65 - 33 = 32 (O) · 45 - 18 = 27 (S) · 54 - 34 = 20 (W) · 119 - 39 = 80 (E) · 88 - 6 = 82 (R) · 36 - 14 = 22 (H) · 65 - 39 = 26 (C) · 60 - 37 = 23 (T) · 112 - 34 = 78 (K)
- Clue 5 (Missing addends): surviving statement (box 3) → Iron Sam4 + ___ = 5 = 1 · 3 + ___ = 14 = 11 · 7 + ___ = 15 = 8 · 9 + ___ = 16 = 7 · 8 + ___ = 10 = 2 · 9 + ___ = 13 = 4 · 3 + ___ = 8 = 5 · 6 + ___ = 18 = 12 · 6 + ___ = 15 = 9 · 10 + ___ = 20 = 10 · 1 + ___ = 7 = 6
About this mystery
- Grade level
- Grade 2 math
- Math topics
- Multiplication, Place value, Addition, Subtraction, Missing addends
- Reading level
- grades 3-4
- Theme
- The Mystery of the Golden Gear — set in Iron Cove Docks
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects