Child (Castrovalva)

A child from Castrovalva once had a brief conversation with the newly-regenerated Fifth Doctor about basic mathematics.

She showed the Doctor how good she was at counting, and he said she should have a badge for mathematical excellence — the mention of which caused the Doctor to remember Adric.

Like all the other residents of the city, the child wasn't real, but rather a block transfer computation creation of the Master. (TV: Castrovalva)