well first we can make a gcf chart 4: 1,2,4 10: 1,2,5,10 we then see that the gcf that they have is 2so 2*2= 4 now for the lcm we can also make a chart 4;4,8,12,16,20,24,28 10; 10,20,30 we see that their lcm is 10. so 10*10=100 hope this helps -turtles12345
