A four-row dilution scan ties every threshold cycle to a PCR source row. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Four twofold standards stay in one checked ladder

The starts are 96,48,24,12. The fixed threshold is 96, so each halving moves the first crossing one cycle later.

96,48,24,1296,48,24,12
Serial dilution threshold ledgerEach twofold dilution shifts the threshold by one exact PCR cycle.starts=96,48,24,12Ct=0,1,2,3shift=0,1,2,3accepted=1

The threshold cycles form a one-step staircase

The checked threshold cycles are 0,1,2,3. The first row starts at the threshold, so its cycle is 0.

0,1,2,30,1,2,3
Serial dilution threshold ledgerEach twofold dilution shifts the threshold by one exact PCR cycle.starts=96,48,24,12Ct=0,1,2,3shift=0,1,2,3accepted=1

The staircase is not an independent table

Starts 96 and 12 cite counts 96 and 96 at their crossing cycles.

96Ct=048Ct=124Ct=212Ct=396\to C_t=0\quad48\to C_t=1\quad24\to C_t=2\quad12\to C_t=3
Serial dilution threshold ledgerEach twofold dilution shifts the threshold by one exact PCR cycle.starts=96,48,24,12Ct=0,1,2,3shift=0,1,2,3accepted=1