Decimal Operations CSI Mystery Worksheets

Inside the case file

Decimal operations worksheets, adding and subtracting decimals practice, multiplying and dividing decimals activities, and powers of ten work for 5th grade and 6th grade math are all included in this CSI Mystery Detective — a no-prep math activity. Students work through all four operations with decimals - lining up the decimal point, working with money to the cent, and moving the decimal point when multiplying and dividing by 10 and 100 - to eliminate suspects and work out which cash bag was taken from the bank vault. Perfect for math centers, spiral review, test prep, sub days and independent practice, and completely no prep - just print and go.

Every clue is built on decimals, so students add, subtract, multiply, divide, compare and order their way through one story. A cash bag has gone from a bank vault that stayed locked all weekend, and only the math will say which one.

What's Inside

• Adding and subtracting decimals to the hundredths, keeping the decimal points lined up: 32.93 + 20.40, 68.79 - 6.87
• Multiplying decimals by whole numbers: 5.3 x 8, 1.25 x 3
• Dividing decimals by whole numbers and by decimals: 38.8 ÷ 4, 4.5 ÷ 0.9
• Multiplying and dividing by 10 and 100 by moving the decimal point: 6.75 x 10, 50 ÷ 100
• Comparing and ordering decimals from smallest to largest: 0.5, 0.84, 1.01, 1.1
• Working with decimals as money - checking bank deposits, withdrawals and balances to the cent
• Complete answer keys
• Full color and ink-saving black and white versions of every page

One full-length case to crack, with every clue building on the last - from a coded message to a bank floor plan the thief escaped through.

What is a CSI Mystery Detective?

A CSI Mystery Detective is a print-and-solve math activity - like an escape room without the locks. Students work through math problems to collect evidence, eliminate suspects, and reveal who did it. It combines real skill practice with critical thinking and a detective hook that keeps the whole class engaged.

When to Use This Resource

• Introducing or consolidating a decimals unit
• Upper elementary and middle school math centers
• Decimal review before state testing
• Warm-ups, morning work and early finishers
• Substitute teacher plans
• Homework and end-of-unit spiral practice
• Whole-class challenge days and enrichment

This decimals CSI Mystery Detective can be used any time you are teaching or revisiting decimal computation. Teachers love it for:

Grade Levels

Designed for 5th grade and 6th grade decimal work. Also beneficial for 7th graders who need more confidence with decimals before pre-algebra, and advanced 4th graders ready for a challenge.

Why Teachers Love CSI Mystery Detective packs

• Feels like a math escape room, with no locks and no technology required
• The detective storyline keeps students working through problem after problem
• Easy prep - simply print and go
• The pages check themselves - a wrong answer stops the mystery in its tracks, so students find their own mistake before it ever reaches your marking pile
• Works for independent practice, partners, small groups or a whole class challenge
• Builds decimal fluency, place value understanding and problem solving together

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