Understanding LCM(15, 25) = 75: The Full Prime Factorization Explained

When solving math problems involving least common multiples (LCM), understanding the underlying number theory is key. One commonly encountered example is finding LCM(15, 25), which equals 75—but what does that truly mean, and how is it derived?

In this guide, we break down LCM(15, 25) using prime factorization to reveal the full reasoning behind why the least common multiple is 3 × 5² = 75. Whether you're a student, educator, or math enthusiast, this explanation will deepen your grasp of LCM and its connection to prime factors.

Understanding the Context


What is LCM?

The least common multiple (LCM) of two or more integers is the smallest positive integer that is divisible by each of them. For example, the multiples of 15 are: 15, 30, 45, 75, 90, ... and multiples of 25 are: 25, 50, 75, 100, .... The smallest shared multiple is 75—confirming LCM(15, 25) = 75.

But why does this number—3 × 5²—carry such significance?

Key Insights


Step-by-Step: Prime Factorization of 15 and 25

To compute LCM, we begin by factoring both numbers into their prime components:

  • 15 = 3 × 5
  • 25 = 5 × 5 =

These prime factorizations reveal the “building blocks” of each number. The LCM is formed by taking each prime factor raised to its highest exponent appearing across the factorizations.

🔗 Related Articles You Might Like:

📰 Top 10 MHA Characters That Defined a Generation—Spill The Tea! 📰 Why MHA Characters Are the Real MVP of Anime Fandoms Today! 📰 You’re Not Ready—Here’s Why ‘MGSV: The Phantom Pain’ Shocks Gamers! – You Won’t Believe What Happens! 📰 So No Such Mathbfv Exists Because The Given Vector Is Not Perpendicular To Mathbfa Violating A Fundamental Identity Mathbfv Imes Mathbfa Perp Mathbfa 📰 So The Largest 3 Digit Multiple Of 7 Is 📰 So The Smallest 3 Digit Multiple Of 7 Is 📰 So Unique Youll Never See This Wedding Dress Againstep Into Fairy Tale Elegance 📰 Solar Contribution 60 Of 25 Gw 060 25 060251515 Gw 📰 Solar Panels 2 2750 2275055005500 📰 Solucin Para Resolver La Ecuacin Sin2Z Cosz Comenzamos Utilizando La Identidad Del Ngulo Doble Para Seno Que Establece Que Sin2Z 2Sinzcosz As La Ecuacin Se Convierte En 📰 Solution After 4 Seconds The Radius Of The Expanding Wavefront Is R 3 Times 4 12 Cm The Area Covered By The Circular Wave Is Given By The Formula For The Area Of A Circle 📰 Solution By The Remainder Theorem The Remainder When Ax3 2 Is Divided By X 5 Is A53 2 So We Must Compute A5 📰 Solution First Compute The Area Of The Triangle Using Herons Formula The Semi Perimeter S Is 📰 Solution For Orthogonality Their Dot Product Must Be Zero 1 Cdot X X Cdot 3 2 Cdot 1 0 Simplifying X 3X 2 0 Rightarrow 4X 2 Rightarrow X Frac12 📰 Solution Let Fx Ax3 Bx2 Cx D We Use The Given Values To Form A System Of Equations 📰 Solution Let Sqrtu T So U T2 Substituting Into The Equation 📰 Solution Let The Integer Be N We Have N Equiv 0 Pmod16 And N Equiv 1 Pmod5 Let N 16K Substituting Into The Second Congruence 📰 Solution Since Angle Aob 90Circ Overrightarrowoa Cdot Overrightarrowob 0 Compute Overrightarrowoc2 4Overrightarrowoa2 Overrightarrowob2 4Overrightarrowoa Cdot Overrightarrowob 44 9 0 25 Thus Overrightarrowoc 5

Final Thoughts


How to Compute LCM Using Prime Exponents

Given:

  • 15 = 3¹ × 5¹
  • 25 =

Now, identify each prime and take the highest exponent:

| Prime | Max Exponent in 15 | Max Exponent in 25 | In LCM |
|-------|---------------------|--------------------|--------|
| 3 | 1 | 0 | 3¹ |
| 5 | 1 | 2 | 5² |

Multiply these together:
LCM(15, 25) = 3¹ × 5²


Simplify the Expression

We simplify:
5² = 25, so:
3 × 25 = 75

Thus, LCM(15, 25) = 75 — expressed compactly as 3 × 5² = 75.