Answer:
504 millimeters (or 50.4 cm)
Step-by-step explanation:
Width of key in student calculator = 14 millimeter (1.4 cm)
Width of key in demonstration calculator = 2.8 cm
Thus, the demonstration calculator's dimensions are twice that of students' (in cm)
Also given, student calculator height as 252 millimeters (25.2 cm)
Thus demonstration calculator height will be twice of that = 50.4 cm (or 504 millimeters)