Hi Sindhu,
You can follow below steps:
1. Create the table required.
2. Then right click on the field required to convert into % and go to add quick table calculation and select % of total.
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3. The field selected has converted to %.
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4. By default tableau perform % of total down the table. If so, to do row wise, right click on the same field and go to compute using and click on across.
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5. Now the table has converted into row wise calculation.
Hope this helps you.
For an in-depth explanation check out Tableau Training Course details.