No. of equilateral triangles required to completely fill a bigger equilateral triangle $\triangle ABC$ is equilateral with side length=2.1cm
Smaller equilateral triangles with side length=1cm are placed over $\triangle ABC$ so that it is fully covered. Find the minimum number of such small triangles.
I am not getting it. How is it possible to completely fill with such dimensions?

This is not answer to the question.
I just post a rough sketch showing a way of how the 6 equilateral triangles can be arranged to cover the original. 
