Question 411258
  <pre><font size = 3 color = "indigo"><b>
Hi
How much 'less' is the sum of all odd digits 'between' 24 and 308 
than the sum of all even digits 'between' 23 and 307?
{{{a[n]=a[1]+(n-1)*d}}}
  306 = 26 + (n-1)2
  306 = 26 + 2n - 2
   282 = 2n
    n = 141
{{{S[n]=(n/2)(2*a[1]+ (n-1)d)}}}
{{{S[141]=(141/2)( 52 + (140)2)}}}  
{{{S[141]=(141/2)(332)}}} = 23,406    |sum of evens

305 = 25 + 2n-2
 141 = n
 141/2(50 + 280) = 141/2*330 = 23,265  |sum of odds

    23,406 - 23,265 = 141