The four networks 192.168.4.0/24, 192.168.5.0/24, 192.168.6.0/24 and 192.168.7.0/24 can be aggregated into a single route

Explanation

The third octets 4–7 share their first six bits (000001xx), so the common prefix is 16 + 6 = 22 bits, i.e. 192.168.4.0/22.