I sell items in lengths of 300mm & 100mm only.

I am trying to write a formula that will look at a whole number, say for example 2800mm, and get the number of 300mm units required, and then add the remainder on in 100mm units (i.e. in this case 9 @ 300 and 1 @ 100). Obviously if its 200mm or below it will end up as 2 No 100mm units.

This is for any whole length from 100 to 3000.

Any help appreciated!