🔎 DetectivesGrade 3Reading: grades 3-4AdditionPlace valueMultiplicationSubtractionMissing addends

The Great Detective Guild Heist

Someone broke into the Master Evidence Vault at Sleuth Academy and swiped the Golden Magnifying Glass. The culprit left encrypted notes and clue clues across the precinct. Help Chief Clara decode the evidence to catch the sneaky rogue.

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	Specialty Tool	Disguise Kit	Stance	Hat Style	Secret Flaw
Nancy	UV Flashlight	Trench Coat	Right Handed	Newsboy Cap	Loud Squeaky Shoes
Watson	Codebook Decoder	Dark Sunglasses	Left Handed	Newsboy Cap	Sneeze From Dust
Nora	Fingerprint Kit	Fake Mustache	Left Handed	Deerstalker	Scared Of Dogs
Marple	Lockpick Set	Fake Badge	Left Handed	Fedora	Loud Squeaky Shoes
Tracy	Codebook Decoder	Bowler Hat	Left Handed	Fedora	Loud Squeaky Shoes
Sam	Codebook Decoder	Trench Coat	Left Handed	Deerstalker	Scared Of Dogs
Poirot	Fingerprint Kit	Trench Coat	Left Handed	Newsboy Cap	Loud Squeaky Shoes
Nick	Fingerprint Kit	Trench Coat	Left Handed	Fedora	Loud Squeaky Shoes
Dupin	Fingerprint Kit	Dark Sunglasses	Left Handed	Fedora	Loud Squeaky Shoes
Hardy	Lockpick Set	Trench Coat	Left Handed	Newsboy Cap	Loud Squeaky Shoes
Spade	Codebook Decoder	Fake Mustache	Left Handed	Deerstalker	Scared Of Dogs
Archy	UV Flashlight	Dark Sunglasses	Right Handed	Deerstalker	Scared Of Dogs
Gidget	Fingerprint Kit	Dark Sunglasses	Left Handed	Newsboy Cap	Sneeze From Dust
Sherlock	Smoke Bomb	Fake Badge	Left Handed	Newsboy Cap	Scared Of Dogs
Fred	UV Flashlight	Trench Coat	Left Handed	Deerstalker	Scared Of Dogs
Enola	Smoke Bomb	Fake Mustache	Left Handed	Newsboy Cap	Loud Squeaky Shoes
Scooby	Lockpick Set	Dark Sunglasses	Left Handed	Fedora	Sneeze From Dust
Daphne	Smoke Bomb	Fake Mustache	Left Handed	Fedora	Loud Squeaky Shoes
Columbo	Codebook Decoder	Dark Sunglasses	Right Handed	Newsboy Cap	Sneeze From Dust
Marlow	Codebook Decoder	Trench Coat	Right Handed	Fedora	Loud Squeaky Shoes
Velma	Codebook Decoder	Fake Mustache	Left Handed	Fedora	Sneeze From Dust

Clue 1

Addition

Chief Clara counted the footprints in the muddy courtyard by combining two sets of tracks.

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

235

404

918

405

692

791

466

880

612

235

381

612

381

746

292

235

692

398

918

251

700

251

865

918

668

251

381

620

918

125 + 110 =T

451 + 467 =E

422 + 190 =I

274 + 418 =U

330 + 370 =F

75 + 176 =A

156 + 225 =D

209 + 196 =C

447 + 344 =L

220 + 400 =G

257 + 147 =H

323 + 423 =N

217 + 249 =P

431 + 237 =B

471 + 409 =R

116 + 176 =O

389 + 476 =K

238 + 160 =S

0/18 letters found

Clue 2

Place value

A digital cipher on the vault lock displays numbers based on hundreds, tens, and ones.

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

1000

6000

600

3000

6000

600

1000

6000

600

1000

6000

300

600

900

6000

3000

100

What is the value of the 1 in 419?W

What is the value of the 6 in 265?H

What is the value of the 3 in 1,134?R

What is the value of the 9 in 5,907?F

What is the value of the 1 in 1,387?I

What is the value of the 8 in 983?N

What is the value of the 9 in 8,392?S

What is the value of the 3 in 13,051?A

What is the value of the 1 in 4,169?D

What is the value of the 3 in 4,399?L

What is the value of the 5 in 7,151?M

What is the value of the 6 in 6,203?T

What is the value of the 6 in 615?E

0/13 letters found

Clue 3

Multiplication facts (1-12)

The detective examined evidence boards arranged in equal rows and columns across the office.

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

7 × 2 =F

10 × 10 =K

2 × 3 =A

12 × 7 =P

10 × 7 =Q

7 × 11 =I

5 × 6 =C

10 × 1 =E

12 × 6 =T

4 × 7 =H

3 × 11 =O

6 × 9 =S

8 × 7 =U

9 × 11 =W

5 × 5 =L

4 × 9 =Y

7 × 6 =D

0/17 letters found

Clue 4

Subtraction

To figure out how many files were taken, the team subtracted the remaining folders from the original pile.

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

315

576

757

791

800

149

315

706

315

187

791

149

800

365

757

791

838

757

315

149

186

254

757

665

315

761

671

186

791

800

149

603 - 288 =A

377 - 191 =T

773 - 108 =V

1045 - 339 =W

1092 - 254 =N

980 - 189 =D

864 - 288 =F

915 - 244 =L

1026 - 269 =E

193 - 6 =S

1021 - 260 =U

746 - 381 =P

403 - 254 =R

257 - 3 =H

1121 - 321 =O

0/15 letters found

Clue 5

Missing addends — the last clue

The suspect left a partial passcode on the keypad, needing one last missing digit to total the vault sum.

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

2 + ___ = 9

6 + ___ = 14

8 + ___ = 14

1 + ___ = 3

10 + ___ = 14

7 + ___ = 18

6 + ___ = 11

8 + ___ = 11

2 + ___ = 12

6 + ___ = 15

8 + ___ = 20

Step 2 — cross out the sentence with each answer

1.The villain vanished into mist with a smoke bomb, then adjusted a fake mustache.

2.The villain decoded the safe with a codebook decoder, then flashed a fake badge.

3.The villain dusted the handle with a fingerprint kit, then flashed a fake badge.

4.The villain vanished into mist with a smoke bomb, then tipped dark sunglasses.

5.The villain decoded the safe with a codebook decoder, then adjusted a fake mustache.

6.The villain dusted the handle with a fingerprint kit, then tipped dark sunglasses.

7.The villain dusted the handle with a fingerprint kit, then swished a heavy trench coat.

8.The villain decoded the safe with a codebook decoder, then adjusted a bowler hat.

9.The villain scratched the vault lock with a UV flashlight, then adjusted a bowler hat.

10.The villain scratched the vault lock with a UV flashlight, then tipped dark sunglasses.

11.The villain scratched the vault lock with a UV flashlight, then adjusted a fake mustache.

12.The villain decoded the safe with a codebook decoder, then tipped dark sunglasses.

Solve it

Name the culprit

Choose the one suspect left standing.

Answer Key — The Great Detective Guild Heist

Culprit: Daphne (Smoke Bomb · Fake Mustache · Left Handed · Fedora · Loud Squeaky Shoes)

Clue 1 (Addition): "THE CULPRIT DID NOT USE A FAKE BADGE"
125 + 110 = 235 (T) · 451 + 467 = 918 (E) · 422 + 190 = 612 (I) · 274 + 418 = 692 (U) · 330 + 370 = 700 (F) · 75 + 176 = 251 (A) · 156 + 225 = 381 (D) · 209 + 196 = 405 (C) · 447 + 344 = 791 (L) · 220 + 400 = 620 (G) · 257 + 147 = 404 (H) · 323 + 423 = 746 (N) · 217 + 249 = 466 (P) · 431 + 237 = 668 (B) · 471 + 409 = 880 (R) · 116 + 176 = 292 (O) · 389 + 476 = 865 (K) · 238 + 160 = 398 (S)
Clue 2 (Place value): "WITNESS SAW THEM WRITE WITH LEFT HAND"
What is the value of the 1 in 419? = 10 (W) · What is the value of the 6 in 265? = 60 (H) · What is the value of the 3 in 1,134? = 30 (R) · What is the value of the 9 in 5,907? = 900 (F) · What is the value of the 1 in 1,387? = 1000 (I) · What is the value of the 8 in 983? = 80 (N) · What is the value of the 9 in 8,392? = 90 (S) · What is the value of the 3 in 13,051? = 3000 (A) · What is the value of the 1 in 4,169? = 100 (D) · What is the value of the 3 in 4,399? = 300 (L) · What is the value of the 5 in 7,151? = 50 (M) · What is the value of the 6 in 6,203? = 6000 (T) · What is the value of the 6 in 615? = 600 (E)
Clue 3 (Multiplication facts (1-12)): "FOOTSTEPS ECHOED WITH LOUD SQUEAKY SHOES"
7 × 2 = 14 (F) · 10 × 10 = 100 (K) · 2 × 3 = 6 (A) · 12 × 7 = 84 (P) · 10 × 7 = 70 (Q) · 7 × 11 = 77 (I) · 5 × 6 = 30 (C) · 10 × 1 = 10 (E) · 12 × 6 = 72 (T) · 4 × 7 = 28 (H) · 3 × 11 = 33 (O) · 6 × 9 = 54 (S) · 8 × 7 = 56 (U) · 9 × 11 = 99 (W) · 5 × 5 = 25 (L) · 4 × 9 = 36 (Y) · 7 × 6 = 42 (D)
Clue 4 (Subtraction): "A FEDORA WAS DROPPED NEAR THE VAULT DOOR"
603 - 288 = 315 (A) · 377 - 191 = 186 (T) · 773 - 108 = 665 (V) · 1045 - 339 = 706 (W) · 1092 - 254 = 838 (N) · 980 - 189 = 791 (D) · 864 - 288 = 576 (F) · 915 - 244 = 671 (L) · 1026 - 269 = 757 (E) · 193 - 6 = 187 (S) · 1021 - 260 = 761 (U) · 746 - 381 = 365 (P) · 403 - 254 = 149 (R) · 257 - 3 = 254 (H) · 1121 - 321 = 800 (O)
Clue 5 (Missing addends): surviving statement (box 1) → Daphne
2 + ___ = 9 = 7 · 6 + ___ = 14 = 8 · 8 + ___ = 14 = 6 · 1 + ___ = 3 = 2 · 10 + ___ = 14 = 4 · 7 + ___ = 18 = 11 · 6 + ___ = 11 = 5 · 8 + ___ = 11 = 3 · 2 + ___ = 12 = 10 · 6 + ___ = 15 = 9 · 8 + ___ = 20 = 12

About this mystery

Grade level: Grade 3 math
Math topics: Addition, Place value, Multiplication, Subtraction, Missing addends
Reading level: grades 3-4
Theme: The Great Detective Guild Heist — set in Sleuth Academy Headquarters
Format: Interactive online & printable worksheet with answer key
Solution: One unique, verified culprit among 21 suspects

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