What is the least common multiple of 8 and 20?

Answer 1

M20
20_40_60

M8
8_16_24_32_40

LCM = 40

Answer 2

A LCM is the lowest multiple, i.e. the smallest number which would have all the given numbers as factors.

The easiest way to calculate an LCM is to factor each number completely, then find the product of all unique factors:

8 = 2*2*2*2
20 = 2*2*5

Now we can come up with a list of common factors that would encompass both numbers as:

2*2*2*2*5 = 40

This group of factors satisfied both 8 (2*2*2*2) and 20 (2*2*5). If we simply put ALL the factors and had (2*2*2*2*2*2*5) we would see this is overkill! Neither number needs more than 4 two's or a single 5.

Hope this helps! :)

Answer 3

To begin, find all the prime factors for 8 and 20

8 and 20 are both even so, you know they are both divisible by two. You do that and you see they are divisible by two again. You get...

8=2x2x2
20=2x2x5

You have two types of prime factors here, 2 and 5.

Now look and see which one has the largest power of 2 and what it is. You see that 8 has 2 three times that is 2^3.

The largest power of five is one.

So (2^3) x 5 = 40 will be your answer

Some Divisibility Rules:

2, if the number is even

3, if when you add all the digits up you get a number divisible by three.

4, if it is divisible by two twice. So it must be even when divided by two

(Also if you just take the tens number and the ones number and add them and get a number divisible by four, it is divisible by four.)

5, if the number ends in 5 or 0

6, see 2 and 3 above

7, I do not recall but I think it is similar to 11

8, similiar to 4 only divisible again by 2

9, passes two consecutive divisibility by three tests

(Also, if the sum of the digits is divisible by nine, it is divisible by nine)

10, ends in 0

11, uses an alternating sum, ask that question please if you really want to know

Answer 4

set it up like this
write out all of the common multiples of each number like this

8- 2, 4
20- 2, 4, 5

the least common multiple is 2

Answer 5

This Site Might Help You.

RE:
What is the least common multiple of 8 and 20?

Answer 6

Lcm Of 20 And 8

Answer 7

40

Answer 8

40

Answer 9

It's been so long I've about forgotten what an LCM is. But I think it is the smallest number that 8 and 20 will both go into evenly. 8x20, of course, both can go into evenly, but maybe it's not the smallest possible number. To find the smallest, you need to prime factor both numbers and build your LCM so that it has as many of each factor as each number, but no more.

For example, 8 is 2x2x2. 20 is 2x2x5. So your answer must have 3 2's (the 2 2's are "covered" because 2x2 will, of course, go into 2x2x2 evenly) and a 5. And 2x2x2x5=40.
Regards, Mike

Answer 10

40

Answer 11

40