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2003 AMC 12B Problems/Problem 18

Revision as of 19:00, 12 June 2008 by El nino (talk | contribs) (New page: suppose n=a*10^4+b*10^3+c*10^2+d*10+e, where a,b,c,d,e are integers between [0,9] then q=a*10^2+b*10+c, r=d*10+e, and (q+r)%11 = n%11, since 10000<n<99999 there are 9090-910+1=8181 n valu...)
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suppose n=a*10^4+b*10^3+c*10^2+d*10+e, where a,b,c,d,e are integers between [0,9] then q=a*10^2+b*10+c, r=d*10+e, and (q+r)%11 = n%11, since 10000<n<99999 there are 9090-910+1=8181 n values that are multiples of 11, thus there are 8181 q+r values that are multiples of 11

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