[Tittywahah]

http://www.sigmaaldrich.com/chemistry/stockroom-reagents/learning-center/technical-library/molarity-calculator.html

If you go here and type in the following:  HCl required:  200mLs at 0.4M and density 1.2 the answer is 6.6mLs

But here is the maths formula I have been using for various calculations for a long time:
0.2L x 0.4M/1L = 0.08
0.08 x 36.5/1 = 2.9g
2.9g/1.2 (density) = 2.4 mLs HCl.

I have double checked triple checked all my notes and reference works, I find no reason to assume I am doing something wrong?

[Borek]

1.2 g/mL is the density of the HCl solution, not of the HCl itself.

[Tittywahah]

I know that Borek. There are 1.2g HCl gas dissolved in 1mL water.  Therefore if I need 2.9g dissolved in water then I need 2.4mLs of the HCl solution.  I learned this ages ago.  Where is the thinking wrong.  And assuming that the website is correct, why are two different chemistry websites wrong?  This is where I got the stoiochemetry from.

I was reading for solids.  I thought this would work, no good at maths but I keep trying. 
So here is the one for solutions:
200 x 0.4/12 = 6.6mLs