Question

I am trying to divide a number into multiple parts so the sum of the part are equal to the input number.

If I have 3.99 and if I need to divide into two parts, the expected output is 2 and 1.99 (2+1.99=3.99)

And if I need to divide 3.99 into 3 parts, the expected output is 1.3, 1.3 and 1.39 (1.3+1.3+1.39=3.99)

I was able to output 2.99 and 1 for the first example and I was able to get 1.99, 1 and 1 for the second example. However, in both the cases results are very far from the expected output.

I need to split postal charges into separate line items. The result could be equally divided or unequally divided while making sure that the sum of the different parts is equal to the input number.

Here are some other examples:

3.99 divided in 3 parts: 1.33, 1.33, 1.33
3.98 divided in 3 parts: 1.33, 1.33, 1.32
3.97 divided in 3 parts: 1.32, 1.32, 1.33
3.96 divided in 3 parts: 1.32, 1.32, 1.32
3.95 divided in 3 parts: 1.32, 1.32, 1.31

Answer 1

I tested with your supplied values. May need some tweaking:

static IEnumerable<decimal> SplitValue2(decimal value, int count)
{
    if (count <= 0) throw new ArgumentException("count must be greater than zero.", "count");
    var result = new decimal[count];

    decimal runningTotal = 0M;
    for (int i = 0; i < count; i++)
    {
        var remainder = value - runningTotal;
        var share = remainder > 0M ? Math.Max(Math.Round(remainder / ((decimal)(count - i)), 2), .01M) : 0M;
        result[i] = share;
        runningTotal += share;
    }

    if (runningTotal < value) result[count - 1] += value - runningTotal;

    return result;
}

This assumes you pass in a value with 2 decimal precision. If you pass in 3.999, you’re not going to get correct results.