Q:

Estimating square numbers

A large dice has a side length of 9.2 cm.
Estimate the surface area of the cube.
What I did:
6× $9^2$
= 6 × 81 = 6 × 80 = 480
But the answer says that $9.2^2$ is 85 as an estimate.
How do I get that?
Thank You

A:

Surface area of dice $=6a^2=6\cdot (9.2)^2=6(\frac{92}{10})^2=6\cdot \frac{92\cdot92}{100}=\frac{50784}{100}=507.84\approx508$ sq. units
However, if you divide this by 6 you will get roughly $85$ sq. units but that is the surface area of one side of dice.

