2009 AMC 10A Problems/Problem 5
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Problem
What is the sum of the digits of the square of 111,111,111 ?
Solution
Using the standard multiplication algorithm, whose digit sum is
Or
Add up all the ones(thus deriving the sum of the number) of gives us
Thus,
See also
2009 AMC 10A (Problems • Answer Key • Resources) | ||
Preceded by Problem 4 |
Followed by Problem 6 | |
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All AMC 10 Problems and Solutions |
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