Question

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. the sum of these multiples is 23.find the sum of all the multiples of 3 or 5 below 1000

Answer 1

step 1 
the sum of all the multiples of 3 below 1000
   =  3+6+9+18+.................+999
  = 3(1+2+3+......................+333)
  = 3 (333 x 334) / 2   (using formula sum of the nos. ={ n x (n+1) } / 2
  =  3 x 55611  = 166833
step 2 
the sum of all the multiples of 5 below 1000
    =  5+10+15+20+..........................+995
    = 5 ( 1+2+3+4+ ............................+ 199)
    =  5 ( 199 x 200) /2
    = 5 x 19900  = 99500
step 3
 the sum of all the multiples of 3 or 5 below 1000
    = 166833 + 99500
    =  266333

Answer 2

Answer:

I SUPPOSE THIS A PRORMMING QUESTION SO HERE IS THE ANSWER

Step-by-step explanation:

for i in range(3):

   num=int(input(''))

   def mul(num,x):

       if num%x!=0:

           num-=num%x

           n=(num//x)+1

           s=(n/2)*(0+(n-1)*x)

       elif num%x==0:

           num-=x

           n=(num//x)+1

           s=(n/2)*(0+(n-1)*x)

       return s

   answer=int(mul(num,3)+mul(num,5)-mul(num,15))

   if answer>0:

       print(answer)