Holding speed fixed makes the drag coefficient the visible source factor. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
One drag coefficient gives four newtons
Hold speed at 4 m/s. Drag coefficient 1 N*s/m gives drag 4 N.
1⋅4=4
Two doubles the drag at the same speed
The speed stays 4 m/s. Coefficient 2 N*s/m gives drag 8 N.
2⋅4=8
Three reaches the twelve-newton base drag
Coefficient 3 N*s/m at the same speed gives drag 12 N. The row remains a toy linear drag law.