Question

What are the least common multiples of 7,14 and 21?

Answer 1

`LCM = 42`

Explanation:

Every number is the lowest multiple of itself, but there is only ever one lowest (least) common multiple of 2 or more numbers.

For the LCM of `7, 14 and 21`, we can ignore `7` completely because it is a factor of the other two numbers, so will automatically be factor of every one of those multiples.

Write each number as the product of the prime factors:

`" "7 = color(white)(xxxxxx)7`
`" "14 = 2color(white)(w.w)xx 7`
`" "21 = ul(" "3xx7)`

`LCM = 2xx3xx7 =42`
`HCF = color(white)(xxxxxx)7`

Answer 2

42

Explanation:

Multiples of 7: 7, 14, 21, 28, 35, 42, 49...
Multiples of 14: 14, 28, 42, 56...
Multiples of 21: 21, 42, 63...

Answer 3

It is 42 !!

Explanation:

Least common multiple simply means the "smallest" number which is common in the multiplication tables of the given set of numbers.

Hence , for 7,14,and 21 it will be 42 as it is the smallest number which is common in the tables of the given numbers .