A mask tells which address bits name the network. The slash prefix is the count of leading ones, and the strip makes that count visible.
Why masks count ones
A prefix mask divides address bits into network bits and host bits. The count after the slash is the count of leading one bits in the mask.
Prefix as leading ones
The /26 mask is 255.255.255.192, or 0xffffffc0. It has 26 leading ones and 6 trailing zeros.
/26⇒0xffffffc0
Decode it again
The /24 mask is 0xffffff00 and 255.255.255.0. A /28 mask would be 0xfffffff0, or 255.255.255.240, so the rule generalizes by counting leading ones.
/24↦0xffffff00
The last byte shows the split
In the /26 mask, the last byte is 192, binary 11000000. That is where the network side stops and the host side begins.
192=11000000
Summary
A prefix length is not decoration; it is the number of leading mask ones. Address arithmetic only; timing/throughput is not modeled here.