Your transaction would return you a gross take-back of 0.21 SGD x 20 x 100 = 420 SGD.

Starting from 2015 : 1 lot = 100 shares only.

If you are still referring to 1 lot as carrying 1000 shares, then your gross take-back would be 4200 SGD.

Subsequently, you would need to minus out the following charges from your transaction :-

1) Brokerage Charge. Since your transaction amt is not big, the minimum brokerage would be imposed, generally = 25 SGD.

2) Clearing and Misc Fees (can't remember the name of the third one), in your case, would not be more than, say about 3 SGD.

Hence, your net take-back would be 420 SGD - (25 SGD + 3 SGD) = 392 SGD.

If your 1 lot = 1000 shares, then your net take-back would be 4200 SGD - (25 SGD + 3 SGD) = 4172 SGD.

Hope the above helps,....