Identify first six /49 blocks out of ABCD::/32

Question

The answer is given as

ABCD:0000:0000:0000:0000::/49 ABCD:0000:0000:0000:8000::/49 ABCD:0000:0000:0001:0000::/49 ABCD:0000:0000:0001:8000::/49 ABCD:0000:0000:0002:0000::/49 ABCD:0000:0000:0002:8000::/49

Please explain me this