How to execute a trade in single trade

In zerodha brokerage are 20rs per trade.

If i place 8 lots nifty option gets executed in parts.5then 2 then total 3 trades and 60 rs brokerage.

How to avoid this

I suppose you are using bracket orders.

You can try cover orders, but here only you can set stop loss value, when you are in profits, you need to manually Exit Cover Order. But the entire 8 lots will be considered as single order with brokerage only 20 rupees for that order.

Otherwise, you can place NRML orders or MIS orders for 8 lots, here also it will be considered as single order and brokerage 20 rs for that 8 lots.

The problem is only with bracket orders (because it uses a background algoz program to set stop loss and target for all executed orders in your trade book for that 8 lots, because we cant fetch the executed prices from order book, only trade book gives you the trade confirmed prices)