Different calculation result using Python

Question

I've got a weird case using Python to get the result of this calculation:

11.66 * 0.98 * 1.05 + 1.7 + 0.70 * 1.03

in Python the result that I got is 14.41914

but when my customer calculate it using their calculator and iPhone the result that they got is 14.8300842

so which is the correct result ? and what caused this calculation to have different result ? thanks

Answer 1

The correct result is the one Python gave you. Your customer is using a calculator that doesn't account for order of operations, or has used the calculator in such a way that order of operations information was discarded.

Answer 2

What your customer seems to have done is this:

>>> (11.66*0.98*1.05 + (1.7+0.7))*1.03
14.830084200000002
>>>

whereas that expression in python:

>>> 11.66*0.98*1.05 + 1.7+0.7*1.03
14.419140000000001

Does the multiplies first:

>>> (11.66*0.98*1.05) + 1.7+(0.7*1.03)
14.419140000000001 

Its a very strong convention that multiplication is done first, but desk calculators (real and appy) have to work on the numbers as they are punched in, so might do different things.