Question: What is the sum of the digits in the decimal form of 2^{1999} * 5^{2002}?

example: 3^{2} * 4^{3} = 9 * 64 = 576 = 5+7+6 = 18

Hi Kelsey,

2^{1999} 5^{2002} = 2^{1999} 5^{1999} 5^{3} = (2 5)^{1999} 5^{3}. The result is a 2002 digit number, but you can find out the sum of the digits without that much calculations.

Claude

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