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How to Simplify Radicals Like Cutting Cake

Why does √72 become 6√2? The "Prison Break" method your math teacher wishes they taught you.

2026-01-27
Algebra
Math Basics
Radicals
Study Tips

Introduction: The Secret Your Calculator Won't Tell You

You type sqrt72sqrt{72} into your calculator, and it spits out 8.48528....

Stop. That is NOT the answer your teacher wants.

Your teacher wants 6sqrt26sqrt{2}. Why? Because decimals are approximations (messy), while radicals are exact values (precise). In architecture, engineering, and advanced math, we need precision. Today, I'll teach you the "Prison Break Method" to handle this without memorizing boring rules.

The Core Concept: "Prison Break" Rules

Imagine the Square Root (sqrtsqrt{}) is a high-security prison.

  • The numbers inside are prisoners.
  • Rule 1: Prisoners must pair up to attempt an escape.
  • Rule 2: For every pair of identical numbers, one escapes to the outside, and the other allows themselves to be caught (disappears).
  • !
    If a number has no partner, it stays in prison forever.

Live Demo: Simplifying sqrt72sqrt{72}

Step 1: Break them down (Prime Factorization)

We need to break 72 down into its most basic building blocks (prime numbers).

  • 72=8imes972 = 8 imes 9
  • 8=2imes4=2imes2imes28 = 2 imes 4 = 2 imes 2 imes 2
  • 9=3imes39 = 3 imes 3
Prisoner List: 2, 2, 2, 3, 3

Step 2: Find the Partners

Look at our list inside the jail:

(2imes2)imes2imes(3imes3)\sqrt{\mathbf{(2 imes 2)} imes 2 imes \mathbf{(3 imes 3)}}
  • We have a pair of 2s.
  • We have a pair of 3s.
  • And one lonely 2 with no friends. 😢

Step 3: The Escape

  • The pair of 2s escapes One 2 makes it outside.
  • The pair of 3s escapes One 3 makes it outside.
  • The lonely 2 stays inside.

Outside World

2imes3=62 imes 3 = 6

Inside Prison

22

Final Answer:

6sqrt26sqrt{2}

Why Learn This?

Sure, you can use our Radical Calculator to get the answer instantly with steps. But on an exam, or when you're calculating exact side lengths of a right triangle, this skill is priceless.

Perfect Squares (The "Mass Breakout")

Some numbers are perfect. Everyone finds a partner, and the prison (radical sign) disappears completely:

sqrt4=2sqrt{4} = 2
sqrt9=3sqrt{9} = 3
sqrt16=4sqrt{16} = 4
sqrt100=10sqrt{100} = 10

But for the rest of the numbers in the universe? That's life. Some things just have to stay inside.

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How to Simplify Radicals Like Cutting Cake | MathIsimple Calculator Guide