1. Examples
1. Find LCM of 30,40 using Prime Factorization Method
Solution: Step-1: Prime factorization of `30,40` using factor by division method
Step-2: Write each number as a product of primes, matching primes vertically when possible
30 | = | 2 | | | × 3 | × 5 | | 40 | = | 2 | × 2 | × 2 | | × 5 | |
Step-3: Bring down the primes in each column. The LCM is the product of these factors
30 | = | 2 | | | × 3 | × 5 | | 40 | = | 2 | × 2 | × 2 | | × 5 | |
| LCM | = | 2 | × 2 | × 2 | × 3 | × 5 | = 120 |
`:.` LCM of `30,40` is `120`
2. Find LCM of 45,25 using Prime Factorization Method
Solution: Step-1: Prime factorization of `45,25` using factor by division method
Step-2: Write each number as a product of primes, matching primes vertically when possible
Step-3: Bring down the primes in each column. The LCM is the product of these factors
45 | = | 3 | × 3 | × 5 | | | 25 | = | | | 5 | × 5 | |
| LCM | = | 3 | × 3 | × 5 | × 5 | = 225 |
`:.` LCM of `45,25` is `225`
3. Find LCM of 50,120 using Prime Factorization Method
Solution: Step-1: Prime factorization of `50,120` using factor tree method
Step-2: Write each number as a product of primes, matching primes vertically when possible
50 | = | 2 | | | | × 5 | × 5 | | 120 | = | 2 | × 2 | × 2 | × 3 | × 5 | | |
Step-3: Bring down the primes in each column. The LCM is the product of these factors
50 | = | 2 | | | | × 5 | × 5 | | 120 | = | 2 | × 2 | × 2 | × 3 | × 5 | | |
| LCM | = | 2 | × 2 | × 2 | × 3 | × 5 | × 5 | = 600 |
`:.` LCM of `50,120` is `600`
4. Find LCM of 400,140 using Prime Factorization Method
Solution: Step-1: Prime factorization of `400,140` using factor tree method
Step-2: Write each number as a product of primes, matching primes vertically when possible
400 | = | 2 | × 2 | × 2 | × 2 | × 5 | × 5 | | | 140 | = | 2 | × 2 | | | × 5 | | × 7 | |
Step-3: Bring down the primes in each column. The LCM is the product of these factors
400 | = | 2 | × 2 | × 2 | × 2 | × 5 | × 5 | | | 140 | = | 2 | × 2 | | | × 5 | | × 7 | |
| LCM | = | 2 | × 2 | × 2 | × 2 | × 5 | × 5 | × 7 | = 2800 |
`:.` LCM of `400,140` is `2800`
5. Find LCM of 30,40,50,60 using Prime Factorization Method
Solution: Step-1: Prime factorization of `30,40,50,60` using factor by division method
Step-2: Write each number as a product of primes, matching primes vertically when possible
30 | = | 2 | | | × 3 | × 5 | | | 40 | = | 2 | × 2 | × 2 | | × 5 | | | 50 | = | 2 | | | | × 5 | × 5 | | 60 | = | 2 | × 2 | | × 3 | × 5 | | |
Step-3: Bring down the primes in each column. The LCM is the product of these factors
30 | = | 2 | | | × 3 | × 5 | | | 40 | = | 2 | × 2 | × 2 | | × 5 | | | 50 | = | 2 | | | | × 5 | × 5 | | 60 | = | 2 | × 2 | | × 3 | × 5 | | |
| LCM | = | 2 | × 2 | × 2 | × 3 | × 5 | × 5 | = 600 |
`:.` LCM of `30,40,50,60` is `600`
This material is intended as a summary. Use your textbook for detail explanation. Any bug, improvement, feedback then
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