SQL SUM / Count(*) vs AVG

My SQL skills  = newbie.
Trying to get the average score from a column using SUM divided by Row Count. Also tried using AVG. Both giving me a slightly different answer.

SELECT SUM(CAST(Erate as int)) / (COUNT(*) * 1.0)  AS TotalAveScore
FROM myTable
WHERE Epublic = 'yes' AND ISNUMERIC([Erate])=1

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RESULT = 4.53086419753086

VS

SELECT AVG(CAST(Erate as int)) *  1.0  AS TotalAveScore
FROM myTable
WHERE Epublic = 'yes' AND ISNUMERIC([Erate])=1

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RESULT = 4.0
swaggerkingAsked:
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Jim HornMicrosoft SQL Server Developer, Architect, and AuthorCommented:
Your big dang deal here is what SQL Server refers to as 'integer math', where an int divided by an int returns an int, and not a numeric with decimal places, e.g. 9 / 2 = the int value 4 and not a numeric value 4.5.

To get around this, CAST either the numerator or the denominator as numeric.

SELECT SUM(CAST(Erate as int)) / CAST(COUNT(*) as numeric(19,4))  AS TotalAveScore
FROM myTable
WHERE Epublic = 'yes' AND ISNUMERIC([Erate])=1
0

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swaggerkingAuthor Commented:
Thanks. Your explanation makes complete sense. Much appreciation.
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