From last two decades wireless networks are gaining popularity and have been widely used. Mobile adhoc network is a great solution to the current need of low-cost, on-demand, autonomous and infrastructure-less network which is highly portable, mobile and temporary in nature. To connect MANET to fixed network, any node in MANET should be configured as a gateway. Node that wants connectivity needs to discover present gateways in MANET. To reduce overhead, previous schemes tune Time to Live and/or Advertisement Interval of gateway advertisement packets based on total source nodes and/or mobility of nodes in MANET. As discussed in [4], it is also possible to consider number of gateways in MANET to adapt the discovery procedure. Proposed scheme does the same. It is found that the new scheme shows better results in terms of less routing overhead with same Delivery Ratio and End-to-End Delay, compared to proactive and hybrid gateway discovery schemes.