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Can someone explain these lines of code?

  Integer count = [SELECT COUNT() FROM Contact];
Integer rand = Math.floor(Math.random() * count).intValue();
Contact c = [SELECT Name FROM Contact LIMIT 10 OFFSET :rand];
Sai PraveenSai Praveen (Salesforce Developers) 

Please find the explanation  for the code.
Integer count = [SELECT COUNT() FROM Contact]; // This is to get the count of contacts in org.

Math.random() function will generate the random number greater than 0 and less than 1 

Math.floor() function will  Returns the largest (closest to positive infinity) Decimal that is not greater than the argument and is equal to a mathematical integer.

intValue() is used to calculate the integer value of the decimal.
Integer rand = Math.floor(Math.random() * count).intValue();// is generating a random number based on the count.
OFFSET is used to skip those many values.

Contact c = [SELECT Name FROM Contact LIMIT 10 OFFSET :rand]; // if the rand variable from above step returns 5 then it will give the result of contact from 6 to 15.
Let me know if you face any issues.

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