hi, guide me,how to make a another way to write again

``````a=1
c=0
d=0
b=1
num1=1
e=1
while b <1000:
b=a*3
a=a+1
c=b+c
while num1<994:
num1=e*5
e=e+1
d=num1+d

print "Here is the sum of multipile by 3 and 5 is %d"%(c+d)``````
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Last Post by tzushky

I think we'd all like to know what exactly the problem is: shortening the code? making it more "profesisonal-like", make functions, ....?

I think you must do the sum of say, all numbers from 1 to x , multiplied by 3, (sum<1000) and same by 5...

Honestly:
s = 1*3 +2*3+...n*3 = (1+2+3+...n)*3 and since s<1000 => 1+2+3+...n< (1000/3)=333

In case you didn't know, 1+2+3+...n = n*(n+1) /2 => n*(n+1) = 666=> n^2 +n - 666 = 0

Delta = 1-4*(1)*(-666) = 2665

=> possible n is = (-1 + sqrt(2665))/2 = 25

So

For your sum multiple by 3 :

``sum3 = sum(range(26))*3    #Because range(26) will take numbers from 0 to 25=n``

And similarly sum5, only a different number will end:

1+...+m < 1000/5 = 200

m(m+1)<400 => m^2+m-400 = 0 is your equation....

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