3-Digit Addition with Regrouping

Inside the case file

3 digit addition with regrouping worksheets, column addition practice and adding within 1000 fluency work for 3rd grade and 4th grade are all included in this pirate Mini Mystery Detective pack of math worksheets. It is made for Talk Like a Pirate Day on September 19, pirate day and pirate week, a pirate classroom transformation, and Halloween dress-up week when you want adventure rather than anything spooky. It fits a treasure hunt, a Golden Age of Piracy topic, an ocean and ships unit, book character day, back to school, and summer school or end-of-year math packets. Completely no prep - just print and go.

Triple digit addition, carrying, regrouping and the standard algorithm all get a full page of practice inside a puzzle students actually want to finish. Printable PDF, black and white and ink friendly, with answer keys for every case - ready for math centers, morning work, homework, spiral review and small group intervention.

What's Inside

• Three digit column addition with regrouping in the ones: 329 + 327, 357 + 508, 229 + 605
• Regrouping in the tens: 550 + 399, 673 + 183, 267 + 651
• Double regrouping across both columns, the step students find hardest: 783 + 198, 499 + 475, 158 + 784
• Straight three digit addition with nothing to carry, so every page starts on solid ground: 625 + 341, 302 + 570
• Adding within 1000 throughout, keeping hundreds, tens and ones lined up where students can see them
• Reading a three digit answer back accurately before committing to it

Five pirate cases to crack: The Missing Treasure, The Captain's Lost Hat, The Vanished Parrot, The Stolen Ship's Wheel and The Black Flag Thief. Answer keys included for every case.

What is a Mini Mystery Detective?

A Mystery Detective is a print-and-solve detective activity - an escape room with no locks, no boxes and no setup. Each page hands students a case, and the math is the only way into it. They solve the problems, work out which of the suspects each answer clears, and the pirate left standing is the culprit.

The pages check themselves - a wrong answer stops the mystery in its tracks, so students go back and find their own slip before it ever reaches your marking pile.

When to Use This Resource

• Talk Like a Pirate Day on September 19
• Pirate day, pirate week and pirate classroom transformations
• Halloween dress-up week, when you want adventure instead of anything spooky
• Treasure hunt, ocean and ships, and Golden Age of Piracy units
• Math centers and rotations
• Morning work and bell ringers
• Homework and spiral review
• Small group work and intervention
• Something worthwhile for students who finish early
• Substitute teacher days
• Back to school, summer school and end-of-year math packets

Grade Levels

Designed for 3rd grade and 4th grade. Also beneficial for 2nd graders who are ready to move past two digit addition, and for 5th graders who need a quick fluency refresh before multi-digit multiplication.

Why Teachers Love Mystery Detectives

• Zero prep - print and go
• Self-checking, so students catch their own mistakes instead of waiting on you
• Prints clean in black and white
• The detective hook carries students through a whole page of computation
• Answer keys for every case
• No seasonal artwork to date it - use it any month, any year

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