set decimal point in SQL

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color:navy;font-weight:bold;font-style:italic;mso-no-proof:yes">I have a field set up as money and I try to calculate
somenumber and put in this field, but the number will be 6 demical point and I want to cut it to only 2-4 decimal
point,how can I do it? Thanks</span></font></i></b></div>