How to calulate qty for futures orders

I’m going crazy trying to calculate the amount to open a position.
I was reading responses to previous posts and came to the following

def qty_order(symbol,price):
usdt_par = futures_functions.get_qtyU(“USDT”)/price #this get the usdt on my wallet and then divide divide by the current price of the currency in which I am going to make the position
minQ = float(client.get_symbol_info(symbol)[‘filters’][2][‘minQty’])
stepS = float(client.get_symbol_info(symbol)[‘filters’][2][‘stepSize’])
b = (usdt_par-minQ)/stepS
quantity = minQ + b * stepS
return quantity

I’m testing with btc and this is the amount that it returns:
and this is the error:
Precision is over the maximum defined for this asset.

I understand why the error comes out, what I’m looking for is a way to calculate the amount

Then I try:

from binance.helpers import round_step_size
stepS = float(client.get_symbol_info(“BTCUSDT”)[‘filters’][2][‘stepSize’])
round_step_size(qty, stepS) - stepS


and again the same error

So my question is how can I calculate the number of correct decimal places in general for any currency?

You should follow the amount of decimal places shown in stepSize filter. For example, if it shows 0.01, this means that the quantity’s decimal place should be 2 or lower.

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