🔎 Books, library, readingGrade 5Reading: grades 5-6Fractions of a numberOrder of operationsMultiplicationRoundingDivision
The Case of the Missing First Edition
Someone snuck into the Rare Books Vault of the Whispering Stacks Library and stole the priceless Golden Codex! Decode the library logs and track down 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 | Special Ability | Library Gear | Dominant Hand | Hair Color | Thievery Weakness |
|---|---|---|---|---|---|
| Ivy Manuscript | Page Freeze | Reading Lamp | Right Handed | Ink Black Hair | Sneeze Powder |
| Mason Paper | Bookmark Blast | Magnifying Monocle | Right Handed | Ink Black Hair | Sneeze Powder |
| Maya Quill | Page Freeze | Magnifying Monocle | Right Handed | Ink Black Hair | Bright Flashlight |
| Mia Ink | Bookmark Blast | Reading Lamp | Right Handed | Paper White Hair | Sneeze Powder |
| Noah Text | Whisper Magic | Leather Satchel | Right Handed | Spine Red Hair | Sneeze Powder |
| Leo Page | Book Shield | Reading Lamp | Left Handed | Spine Red Hair | Loud Alarm |
| Eli Author | Page Freeze | Magnifying Monocle | Right Handed | Ink Black Hair | Sneeze Powder |
| Nora Binding | Page Freeze | Reading Lamp | Left Handed | Ink Black Hair | Bright Flashlight |
| Jack Cover | Bookmark Blast | Leather Satchel | Left Handed | Ink Black Hair | Bright Flashlight |
| Ezra Shelf | Bookmark Blast | Magnifying Monocle | Right Handed | Ink Black Hair | Loud Alarm |
| Chloe Index | Page Freeze | Glowing Quill | Left Handed | Ink Black Hair | Sneeze Powder |
| Clara Book | Page Freeze | Silver Stamp | Right Handed | Paper White Hair | Sneeze Powder |
| Caleb Journal | Page Freeze | Silver Stamp | Right Handed | Paper White Hair | Bright Flashlight |
| Grace Margin | Bookmark Blast | Magnifying Monocle | Left Handed | Spine Red Hair | Loud Alarm |
| Sarah Spine | Book Shield | Leather Satchel | Left Handed | Paper White Hair | Sneeze Powder |
| Liam Atlas | Whisper Magic | Leather Satchel | Right Handed | Ink Black Hair | Sneeze Powder |
| Ruby Reader | Ink Spray | Silver Stamp | Right Handed | Paper White Hair | Bright Flashlight |
| Sam Vellum | Ink Spray | Reading Lamp | Left Handed | Paper White Hair | Loud Alarm |
| Hugo Story | Page Freeze | Glowing Quill | Left Handed | Spine Red Hair | Bright Flashlight |
| Owen Folio | Page Freeze | Leather Satchel | Right Handed | Ink Black Hair | Sneeze Powder |
| Fiona Novel | Page Freeze | Magnifying Monocle | Left Handed | Ink Black Hair | Loud Alarm |
Clue 1
Fractions of a number
The Head Librarian found a partial catalog list showing only a fraction of the missing ledger entries.
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
14
38
6
8
31
7
7
29
31
18
34
19
6
36
18
19
T
14
27
36
6
29
33
6
29
34
31
18
39
7
29
24
23
1/2 of 28 =T
2/4 of 46 =P
2/4 of 16 =V
3/10 of 90 =U
4/8 of 62 =I
2/4 of 58 =A
3/6 of 78 =G
7/10 of 10 =L
5/10 of 76 =H
1/3 of 18 =E
1/5 of 180 =S
3/8 of 48 =N
2/3 of 51 =D
1/2 of 66 =R
2/8 of 96 =M
2/4 of 38 =O
0/16 letters found
Clue 2
Order of operations
To decrypt the cipher on the checkout desk terminal, solve this multi-step equation in the proper order.
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
58
52
69
51
8
51
42
69
18
T
58
71
37
51
71
50
27
T
58
27
68
63
71
27
T
58
52
37
50
27
63
52
T
58
52
37
68
64
34 + 4 × 6 =T
10 × 7 - 7 =G
3 + 3 × 5 =C
6 × 6 - 28 =U
5 × 12 - 10 =R
9 × 10 - 19 =W
8 × 10 - 29 =S
9 × 6 - 2 =H
10 × 9 - 22 =N
13 + 7 × 2 =I
37 + 9 × 3 =D
18 + 6 × 4 =P
7 + 5 × 6 =A
12 × 8 - 27 =E
0/14 letters found
Clue 3
Multiplication facts (1-12)
The thief organized rows of book crates in identical stacks near the back exit.
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
22
88
28
80
9
96
80
15
5
72
60
60
84
60
4
80
66
96
60
10
96
9
5
120
60
96
120
35
60
15
28
80
80
10
2 × 11 =A
8 × 12 =D
7 × 12 =Z
7 × 4 =L
11 × 8 =C
1 × 10 =R
5 × 7 =H
5 × 1 =S
10 × 6 =E
2 × 2 =P
3 × 3 =U
12 × 6 =N
11 × 6 =W
12 × 10 =T
3 × 5 =F
10 × 8 =O
0/16 letters found
Clue 4
Rounding
The digital security scanner on the library door only displays rounded page counts.
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
4300
7000
290
2900
900
50
S
4300
370
200
430
900
230
1700
2300
2900
700
230
30
2900
430
290
1300
1100
290
1100
430
900
S
4300
7000
2900
700
230
S
4300
Round 4,325 to the nearest hundredS
Round 29 to the nearest tenH
Round 249 to the nearest hundredF
Round 680 to the nearest hundredC
Round 6,911 to the nearest thousandT
Round 52 to the nearest tenD
Round 432 to the nearest tenI
Round 2,321 to the nearest hundredL
Round 2,920 to the nearest hundredA
Round 1,094 to the nearest hundredE
Round 233 to the nearest tenK
Round 897 to the nearest hundredN
Round 373 to the nearest tenO
Round 289 to the nearest tenR
Round 1,253 to the nearest hundredW
Round 1,693 to the nearest hundredB
0/16 letters found
Clue 5
Division facts (1-12) — the last clue
The Archive Patrol is splitting up the remaining library aisles equally to search for clues.
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
70 ÷ 10 = ?
84 ÷ 7 = ?
36 ÷ 4 = ?
56 ÷ 7 = ?
3 ÷ 3 = ?
30 ÷ 5 = ?
5 ÷ 1 = ?
3 ÷ 1 = ?
66 ÷ 6 = ?
24 ÷ 6 = ?
20 ÷ 2 = ?
Step 2 — cross out the sentence with each answer
1.The villain whispered magic into the stacks, then inspected the vault with a monocle.
2.The villain sprayed ink across the aisle, then inspected the vault with a monocle.
3.The villain froze the book pages solid, then lit up the hall with a reading lamp.
4.The villain blasted bookmark cards everywhere, then inspected the vault with a monocle.
5.The villain whispered magic into the stacks, then escaped with a glowing quill.
6.The villain blasted bookmark cards everywhere, then marked the shelf with a silver stamp.
7.The villain froze the book pages solid, then stashed the loot in a leather satchel.
8.The villain blocked the door with a book shield, then escaped with a glowing quill.
9.The villain whispered magic into the stacks, then stashed the loot in a leather satchel.
10.The villain sprayed ink across the aisle, then stashed the loot in a leather satchel.
11.The villain blocked the door with a book shield, then lit up the hall with a reading lamp.
12.The villain froze the book pages solid, then inspected the vault with a monocle.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Case of the Missing First Edition
Culprit: Mason Paper (Bookmark Blast · Magnifying Monocle · Right Handed · Ink Black Hair · Sneeze Powder)
- Clue 1 (Fractions of a number): "THE VILLAIN DOES NOT USE A READING LAMP"1/2 of 28 = 14 (T) · 2/4 of 46 = 23 (P) · 2/4 of 16 = 8 (V) · 3/10 of 90 = 27 (U) · 4/8 of 62 = 31 (I) · 2/4 of 58 = 29 (A) · 3/6 of 78 = 39 (G) · 7/10 of 10 = 7 (L) · 5/10 of 76 = 38 (H) · 1/3 of 18 = 6 (E) · 1/5 of 180 = 36 (S) · 3/8 of 48 = 18 (N) · 2/3 of 51 = 34 (D) · 1/2 of 66 = 33 (R) · 2/8 of 96 = 24 (M) · 2/4 of 38 = 19 (O)
- Clue 2 (Order of operations): "THE SUSPECT WAS WRITING WITH A RIGHT HAND"34 + 4 × 6 = 58 (T) · 10 × 7 - 7 = 63 (G) · 3 + 3 × 5 = 18 (C) · 6 × 6 - 28 = 8 (U) · 5 × 12 - 10 = 50 (R) · 9 × 10 - 19 = 71 (W) · 8 × 10 - 29 = 51 (S) · 9 × 6 - 2 = 52 (H) · 10 × 9 - 22 = 68 (N) · 13 + 7 × 2 = 27 (I) · 37 + 9 × 3 = 64 (D) · 18 + 6 × 4 = 42 (P) · 7 + 5 × 6 = 37 (A) · 12 × 8 - 27 = 69 (E)
- Clue 3 (Multiplication facts (1-12)): "A CLOUD OF SNEEZE POWDER DUSTED THE FLOOR"2 × 11 = 22 (A) · 8 × 12 = 96 (D) · 7 × 12 = 84 (Z) · 7 × 4 = 28 (L) · 11 × 8 = 88 (C) · 1 × 10 = 10 (R) · 5 × 7 = 35 (H) · 5 × 1 = 5 (S) · 10 × 6 = 60 (E) · 2 × 2 = 4 (P) · 3 × 3 = 9 (U) · 12 × 6 = 72 (N) · 11 × 6 = 66 (W) · 12 × 10 = 120 (T) · 3 × 5 = 15 (F) · 10 × 8 = 80 (O)
- Clue 4 (Rounding): "STRANDS OF INK BLACK HAIR WERE IN STACKS"Round 4,325 to the nearest hundred = 4300 (S) · Round 29 to the nearest ten = 30 (H) · Round 249 to the nearest hundred = 200 (F) · Round 680 to the nearest hundred = 700 (C) · Round 6,911 to the nearest thousand = 7000 (T) · Round 52 to the nearest ten = 50 (D) · Round 432 to the nearest ten = 430 (I) · Round 2,321 to the nearest hundred = 2300 (L) · Round 2,920 to the nearest hundred = 2900 (A) · Round 1,094 to the nearest hundred = 1100 (E) · Round 233 to the nearest ten = 230 (K) · Round 897 to the nearest hundred = 900 (N) · Round 373 to the nearest ten = 370 (O) · Round 289 to the nearest ten = 290 (R) · Round 1,253 to the nearest hundred = 1300 (W) · Round 1,693 to the nearest hundred = 1700 (B)
- Clue 5 (Division facts (1-12)): surviving statement (box 2) → Mason Paper70 ÷ 10 = 7 · 84 ÷ 7 = 12 · 36 ÷ 4 = 9 · 56 ÷ 7 = 8 · 3 ÷ 3 = 1 · 30 ÷ 5 = 6 · 5 ÷ 1 = 5 · 3 ÷ 1 = 3 · 66 ÷ 6 = 11 · 24 ÷ 6 = 4 · 20 ÷ 2 = 10
About this mystery
- Grade level
- Grade 5 math
- Math topics
- Fractions of a number, Order of operations, Multiplication, Rounding, Division
- Reading level
- grades 5-6
- Theme
- The Case of the Missing First Edition — set in The Whispering Stacks Library
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects