Its actually quite easy, technically, it's written as 0.5p or you can write it as a fraction. There used to be half a penny coin too so maybe, if you found out the calculational term for that, it should give you an 100% accurate answer although this is quite close.
One half percent can be written in decimal as 0.005 or just .005
It is 0.005
i penny is 1 out of 100 cents, therefore it is .01
2 1/2 written in decimal form is 2.5
Fifteen tenths, in decimal form, is written as 1.5 which is also equal to one and a half.
The British decimal Half New Penny and Half Penny coins were demonetised and withdrawn from circulation in December 1984.
7 halves = 3.5
We write two and a half as 2.5 in decimal form.
The number one and a half as 1.5 in decimal form.
A half written as a decimal is 0.5
1 half in decimal form = 0.5