Voltage ratio and inverse current ratio keep ideal transformer power balanced. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Two-to-four turns doubles voltage
Turns 2 to 4 carry voltage 4 V to 8 V while currents 4 A and 2 A both close power 16 W.
Pp=4×4=16,Ps=8×2=16
Three-to-six turns halves current
Turns 3 to 6 carry voltage 6 V to 12 V while currents 2 A and 1 A both close power 12 W.
Pp=6×2=12,Ps=12×1=12
Four-to-eight turns still conserves power
Turns 4 to 8 carry voltage 8 V to 16 V while currents 2 A and 1 A both close power 16 W.