Thanks for the reply and sorry for my poor explanation. Basically I have equipment that comes in set lengths apart from the first three metres. The lengths are as follows 0.5 metre 1 metre 1.5 metre 2 metre 2.5 metre 3 metre all the others go up in increments of one meter until a point and then go up in two meter increments. So everything below the figure three goes up from 0 to 3 in 0.5 increments that's why I asked for greater than 3 as I was going to tackle the below figures separately being a novice however if you can include the below and above figures in the one equation I would be knocked over thanking you in advance