Hi Experts,

I have a dataset of 3 columns:

customer.name     product     cost
John     Toothpaste     30
Mike     Toothpaste     45
Peter     Toothpaste     40

And I have a function of cost whereby

cost = 3.40 + (1.20 * no.of.orders^2)

I want to do a backward calculation for each records (each customer) to
find his no.of.orders and create a new column named "no.of.orders" in that
dataset but I don't know how to do.

Please help me.

Thank you everyone,
Prakasit

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