A clean codeword divides evenly by the generator. The verify matrix recomputes that zero remainder from the transmitted bits.
highlighted = computed this step
Why verification divides the whole codeword
A receiver divides the complete codeword, not just the original message. A clean codeword is divisible by the generator.
remainder=000
Remainder zero means no detected error
Dividing codeword 11010011101100100 by 1011 leaves remainder 000. That means no error is detected.
11010011101100100mod1011=000
Why this works
The sender chose the CRC so message plus CRC is divisible by the generator. Verification checks that divisibility again.
zero remainder=000
Summary
CRC verification recomputes divisibility over the complete codeword and expects a zero remainder. Polynomial arithmetic over the exact bits; timing/throughput is not modeled here.