Given,
Length, L = 8 m 50 cm = 850 cm =21×52×17
Breadth, B = 6m 25cm = 625 cm 54
Height, H = 4m 75cm = 475 cm =52×19
The longest rod that can measure the dimensions of the room exactly, will be equal to the HCF of length,breadth and height of the room.
∴ HCF of L, B and H is 52 = 25cm
∴ Length of the longest rod = 25 cm