Gratuity calculation if previous service gratuity transferred to the current employer

Thanks for reply,

but below given formula is mentioning only current employer, please advise:

Using the Gratuity Calculator Formula, one can determine the gratuity amount.

Gratuity (G) = n*b*15/26

n = The number of completed years in the current organization

b = the Last drawn basic monthly salary (plus dearness allowance, the commission received on sales, if any)