Based on the price of each stock in a smallcase and their prescribed weights, a minimum investment amount is calculated that allows you to buy all stocks at the closest weightage to that intended.
You can also increase the amount you want to invest in that smallcase by entering a greater number, and hit confirm to get the closest amount that gives you the right weighting scheme. Be advised, you'd not be able to invest lesser than the minimum amount.
The minimum amount for each smallcase is different & changes in real-time - you can see the current minimum investment amount on the smallcase page as shown below.
For more info on the amount being used for smallcase and on Fund Transfers, click here
You can also filter smallcases by their Minimum Investment Amount on the Discover page like so: