What is the LCM of 980 100 2450 140?

Answer 1

To find the LCM of a set of numbers you first need to break those numbers down into their prime factors. In this case:

980 = 2x2x5x7x7

100 = 2x2x5x5

2450 = 2x5x5x7x7

140 = 2x2x5x7

The next step is to identify any common prime factors between the numbers, and only count them once. In this case, all numbers contain one 2 and one 5, so 3 of each can be dismissed. Two numbers also contain a second 5 so one of these can be dismissed. Three numbers contain a second 2 so 2 of these can be dismissed. 3 numbers contain a 7, so 2 of these can be dismissed, and two numbers contain a second 7 so 1 of these can be dismissed.

We are left with:

2,2,5,5,7,7

Multiplying these together we get 4,900

So the LCM of 980, 100, 2450 and 140 is 4,900