If you had a position that consisted of fractional units (e.g 0.2, 0.5, 1.3 etc) prior to the split, its quantity will be rounded down after the split and only a whole number of shares will be left. In this case, for example, a 0.3 presplit quantity of shares will result in:
0.3 (Quantity) x 4 (Split coefficient) = 1.2 Shares = 1 Share left in position + 0.2 Fractions to be sold.
The whole number is the new adjusted quantity of your position, while the split fractions are sold at the last available price and the result is paid to your account.
You will see the Profit/Loss from the sale of the fractional shares in Transactions, while the capital invested in them will be released and appear in your Free Funds, available for reinvestment. The amount of the unblocked sum to your Free funds is not yet displayed/visible as a transaction, apart from the increase of the Total Free Funds, but we are working hard to make it more intuitive for future stock splits.
If you want to know more about how the result applied to your Transactions is calculated, you need to follow the next few steps. The example is concerning the 4for1 stock split of Apple and in this article, you will find information about the 5for1 stock split of Tesa last available price.
Feel free to use the calculations below and simply replace the information relevant to your account.
General Information
Apple stock  last available price* 
499.01 USD 
Tesla stock  last available price* 
2212.26 USD 
The exchange rate** at the time of the split: 

GBP/USD 
1.34145166098 
EUR/USD 
1.19660904444 
 The last available price is the price at which the stock closed its last presplit trading session and is the basis for the sale of the fractional shares and your positions adjustment.
 If the currency of the account differs from the quoted currency of the instrument that you’re trading, then a currency conversion should take place. Example: if your account is in GBP, however, you’re trading Apple > the exchange rate above should be applied
Profit/Loss Formulas
The following formulas will help you calculate the Profit/Loss of the fractions sale (Visible in your Transactions Tab) and the freed capital in your Free Funds. Before we proceed, we'll need to gather some additional information for the formulas:
 Quantity before split  0.2849978
 Quantity after split  1.1399912 (Quantity before split * Split Coefficient)
 Remaining Quantity Sold  1.1399912  1 = 0.1399912
 Average price  459.5825
 Average Exchange Rate  1.3098
I. Remaining Quantity Sold
The fractions in excess of the whole number of shares in the adjusted quantity:
(Presplit quantity * Stock split coefficient)  (Whole units) (i.e. X,YZ  X = 0.YZ)
II. Profit / Loss
(Last available price of the instrument  Average price of the position) / Stock split coefficient) * Remaining quantity sold
III. Freed Capital in your Total Free Funds
(Average price of the position) / Stock split coefficient) * Remaining quantity sold
NonUSD currency accounts
The following step is optional for accounts with a currency different from US dollars. You'll need to merely replace the prices in the formula with the converted value.
 Last available price: 499.01 USD / 1.34145166098 (GBP/USD) = 371.9925 GBP
 Average price: 459.5825 USD / 1.3098 (GBP/ USD) = 350.8799 GBP
If you had more than one modification, you must calculate the average exchange rate of all orders:
(Exchange rate1 * Quantity) + (..) + (Exchange rate * Quantity) + (Exchange raten+1 * Quantity) / Total Quantity
Оnce you have all the numbers you need to simply apply them to the formulas above. Here's an example calculation:
I. Remaining Quantity Sold
1.1399912  1 = 0.1399912
II. Profit / Loss
(371.9925  350.8799) / 4)* 0.1399912 = 0.74 GBP***
III. Freed Capital in your Total Free Funds
(350.8799 / 4) * 0.1399912 = 12.28 GBP*
***Please note that there might be slight discrepancies in the range of 1p due to the fact the numbers on the application are shown with lower precision, while the exchange rate precision might be up to the 11th decimal place.