HRA exemption

Hi ,

I entered HRA 40% on basic pay in 0008 IT.Calculation coming correctly .HRA is 16,667.00

than 581IT (Housing(HRA / CLA / COA)) created

Accommodation Type:Rented accom

City Category:Non -metro

Rent Amount 20,000.00 INR ,selected check box HRA to be tax exempt

executed pay roll .

/4E4 HRA Annual Exemption= 186,832.94

how it arrived this amount

How much amount is HRA exemption , How do I check in RT table.

Regards

Nandhini