Explain how to find 40x80 using mental math

Lcm of 6 and 8 is 24lcm of 4 and 12 is 12lcm of 11 and 12 is 132 lcm of 3 and 6 is 6

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.