



 
Joan, It is the number where the exponent of 2 is between 21 and 40 OR the exponent of 5 is between 21 and 40. This is the number where the exponent of 2 is as described (between 21 and 40) plus the number where the exponent of 5 is as described, minus the number where both exponents are as described. This is 20x41 + 20x41  20x20. Victoria  


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