I need to find the least common multiple (lcm) of 20,15,and 35 anyone help?

Question

This is a huge number....I came out with an answer but doubt its right. I need help with this, thanks.

Answer 1

20 = 5 x 4
15 = 5 x 3
35 = 5 x 7

They have 5 in common.
LCM = 5 x 4 x 3 x 7 = 60 x 7 = 420

Answer 2

Factor each number, and note which factors are common to all three numbers. In this case:
2 x 2 x 5; 3 x 5, and 7 x 5. Here, the only common factor is 5. Extract that from each of the products, and multiply it by the product of what is left: 5 x (2 x 2) x (3) x (7). The result is the least common multiple, in this case 420.

Answer 3

Here's an interesting tip for doing LCMs - break each number down into prime numbers.

The primes that go into each number are:
20: 2, 2,, 5
15: 3, 5
35: 5, 7

Now, count the primes
20: 2 (one), 5 (one)
15: 3 (once), 5 (once)
35: 5 (one), and 7 (one)

Now you take each prime number, and multiply it by the maximum number times it was used IN ANY ONE NUMBER.

3, 5, and 7 were each used once. Two was used twice.

Multiply the primes
2*2*3*5*7 = 420

Answer 4

well..
break them all down...

20:
2*10 = 2*2*5

15:
3*5

35:
5*7

Now multiply all the factors together... but dont include factors that are common to all the numbers:
lcm = 2*2*3*5*7 = 420

Answer 5

20 = 2*2*5
15 = 3*5
35 = 5*7
LCM = 7*5*3*4 = 420

Answer 6

put each in to multiples of prime numbers
20= 5*2*2
15=5*3
35=5*7
Then use all the primes necessary to make any one number.

i.e. 5*2*2*3*7 = 420

Answer 7

420

Answer 8

420

Answer 9

5 is the least common multiple

Answer 10

they are all multiples of 5.