perplexus.info :: Just Math : S(2*N) ≤ 2*S(N) ≤ 10*S(2*N)

S(2*N) ≤ 2*S(N) ≤ 10*S(2*N) (Posted on 2010-01-16)

S(N) denotes the sum of the digits of a base ten positive integer N.

Prove that:

S(2*N) ≤ 2*S(N) ≤ 10*S(2*N)

See The Solution Submitted by K Sengupta

Rating: 5.0000 (1 votes)

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