Erin had to find the product of 2^2007 and 5^2000 and then calculate the sum of the digits of the answer. Erin arrived at an answer of 11.Is she correct? Show ALL the calculations to motivate your...

Erin had to find the product of 2^2007 and 5^2000 and then calculate the sum of the digits of the answer. Erin arrived at an answer of 11.Is she correct? Show ALL the calculations to motivate your answer

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aruv | High School Teacher | (Level 2) Valedictorian

Posted on

 Yes ,she is correct because

`2^2007xx5^2000=2^(2000+7)xx5^2000`

`=2^7xx2^2000xx5^2000`

`=2^7xx(2xx5)^2000`

`=128xx10^2000`

`Thus`

`1+2+8+0+0+.........+0 =11` 

(0+0+0+...+0 ,2000  times)

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