400
200,2
100,2,2
50,2,2,2
25,2,2,2,2
5,5,2,2,2,2
400 200,2 100,2,2 50,2,2,2 25,2,2,2,2 5,5,2,2,2,2
Use a factor tree. 400 200,2 100,2,2 50,2,2,2 25,2,2,2,2 5,5,2,2,2,2
We generally don't do factor trees of negative numbers, since factor trees are designed to obtain the prime factorization and negative numbers don't have prime factorizations. Here's 400: 400 200,2 100,2,2 50,2,2,2 25,2,2,2,2 5,5,2,2,2,2
Use a factor tree. 400 20,2 10,2,2 50,2,2,2 25,2,2,2,2 5,5,2,2,2,2 2 x 2 x 2 x 2 x 5 x 5 = 400
24 x 52 = 400
400 200,2 100,2,2 50,2,2,2 25,2,2,2,2 5,5,2,2,2,2
400 200,2 100,2,2 50,2,2,2 25,2,2,2,2 5,5,2,2,2,2
10 squared times 2squared
2 to the 4th times 5 squared
22 x 5 = 20
Well, honey, the lowest common factor of 60 and 400 is 20. It's like finding the least annoying song on the radio - not too difficult if you know what you're doing. So there you have it, 20 is the magic number that both 60 and 400 can agree on.
400 = 2^4 × 5^2