Question

find the least number that can be divided exactly by all even numbers between 10 and 20

Answer 1

That would be the l.c.m. of all those numbers.
2 l_12,_14,_16,_18___
2 l__6,__7,__8,__9___
2 l__3,__7,__4,__9___
2 l__3,__7,__2,__9___
3 l__3,__7,__1,__9___
3 l__1,__7,__1,__3___
7 l__1,__7,__1,__1___
  l__1,__1,__,1,__1___
LCM(12,14,16,18) = 2 X 2 X 2 X 2 X 3 X 3 X 7
                          = 1008

Answer 2

LCM(12,14,16,18) = 2 X 2 X 2 X 2 X 3 X 3 X 7
                          = 1008

1008 is the answer