In Python 3, how do I round a floating point number up to a certain decimal place?

Question

I have 12.5, and I want to convert it to 13. How can I do this in Python 3?

The task was like this - "Given the meal price (base cost of a meal), tip percent (the percentage of the meal price being added as tip), and tax percent (the percentage of the meal price being added as tax) for a meal, find and print the meal's total cost"

I solved the problem in Python 3 and in 3 test cases, it shows that my code is working. but in 1 case it is not.

Where,

Sample input:

12.00

20

8

Expected output:

13

And my output was 12.5

How on earth I can take 12.5 as 13?

mealcost = float(input()) 
tippercent = float(input()) 
taxpercent = float(input())  

tippercent = mealcost * (tippercent / 100)  
taxpercent = mealcost * (taxpercent / 100) 

totalcost = float( mealcost + tippercent + taxpercent)  
print(totalcost)

Use the built-in function round(value[,ndigits]) see https://docs.python.org/3.5/library/functions.html#round — barny, Nov 27 '18 at 22:23
That makes no sense - $12 base cost with 20% tip and 8% tax works out to $15.36 (assuming tip and tax are both calculated from the base cost). Neither 13 nor 12.5 is correct. — user2357112 supports Monica, Nov 27 '18 at 22:24
duplicate? https://stackoverflow.com/questions/56820/round-in-python-doesnt-seem-to-be-rounding-properly — hiro protagonist, Nov 27 '18 at 22:24

score 1 · Answer 1 · answered Nov 27 '18 at 22:20

1

Use round()

print(round(12.5))
>>> 13.0

answered Nov 27 '18 at 22:20

berkelem

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You forgot the optional ndigits parameter see https://docs.python.org/3.5/library/functions.html#round – barny Nov 27 '18 at 22:24
1

`round` will round 12.5 to 12 on Python 3. – user2357112 supports Monica Nov 27 '18 at 22:25

Joran Beasley · Answer 2 · 2018-11-27T22:27:46.410

-2

To round to the nearest X (ie nearest 20.0)

just divide by the value you want to round to
then round the result
then multiply it by the number you want to round to and cast to an int

for example

round_to_nearest = 20
for a_num in [9,15,22,32,35,66,98]:
    rounded = int(round(a_num/round_to_nearest)*round_to_nearest)
    print("{a_num} rounded = ".format(a_num=a_num,r=rounded))

to just round

oh nevermind it looks like you just want

print(round(12.3),round(12.6)) # 12, 13

if round rounds wrongly (ie round(12.5) => 12 in python3) you can just add 0.5 to your number and floor it

int(12.5+0.5)

edited Nov 27 '18 at 22:27

answered Nov 27 '18 at 22:21

Joran Beasley

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Round() does all this, without you typing so much – barny Nov 27 '18 at 22:24
the OP didn’t mention rounding to the nearest 20. Read the title of the question. – barny Nov 27 '18 at 22:27
Nearest 20?!?!? – barny Nov 27 '18 at 22:40
just `round(12.5)` – Joran Beasley Nov 27 '18 at 22:43

In Python 3, how do I round a floating point number up to a certain decimal place?

2 Answers2

To round to the nearest X (ie nearest 20.0)

to just round