MySQL 8.0

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CREATE TABLE numbers (num INT)
WITH RECURSIVE
cte AS ( SELECT 1 num
         UNION ALL
         SELECT num + 1
         FROM cte
         WHERE num < 10 )
SELECT num FROM cte;

Records: 10  Duplicates: 0  Warnings: 0

SET @arg := '800, 776, 7803, 827, 91, 976, 908';
SELECT @arg;

@arg

800, 776, 7803, 827, 91, 976, 908

SELECT myCol*10
FROM ( SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(@arg, ',', numbers.num), ',', -1) as myCol 
       FROM numbers 
       WHERE numbers.num <= LENGTH(@arg) - LENGTH(REPLACE(@arg, ',', '')) + 1 ) source;

myCol*10

8000

7760

78030

8270

910

9760

9080