Respuesta :

First, we list the prime factors of all the numbers:

40 = 2 * 2 * 2 * 5

70 = 2 * 5 * 7

80 = 2 * 2 * 2 * 2 * 5

Now, we see the unique factors. They are:

2, 5, and 7

We take each of these the highest number of time it occurs in any of the numbers.

2 occurs 4 times in 80

5 occurs 1 times highest, so does 7

Hence, the LCM would be:

LCM = 2 * 2 * 2 * 2 * 5 * 7

Which is

560