Can i split average of many photos.

Hi. 

I need to average(median) around 50 photos.

The problem is im on super old hardware, x5450 xeon with 8gb od ram. GPU GTX 650ti. 200gb ssd scrach disk. 

When i try to stack and average, it will crash Photoshop at some point.

I can average 10 photos at max.

The questions.

Can i average by 10, and then average the 5 resulting images? 

Will this give me the same quality that if i done them all at once?

Sorry for my english.