Assuming that i have seed bag sizes of 1kg, 2 kg, and 5kg. And my clients typically have a land size between 0.25 and 5 acres and will plant 10kgs per acre.
What formualar can i use to calculate for each client the number of 5kg, 2kg and 1kg seed bags they need for planting. In the calculation, i want to try to assign the larger bags first while avoiding to assign half bags to a client as much as possible.
Let $m$ be the seeds in kilograms you need and $b_i$ be the number of bags of size $i$ kilograms needed.
Then
$b_5=\left\lfloor\frac{\lceil m\rceil}{5}\right\rfloor$
$b_2=\left\lfloor\frac{\lceil m\rceil-5b_5}{2}\right\rfloor$
$b_1=\lceil m\rceil-5b_5-2b_2$
Don't think there is a much nicer explicit formula.
There's always the option of calculating all the possibilities beforehand (there's only 50 of them and using a program is possible).