What is the Average Angular Speed of the Leaning Tower of Pisa?

[R.H.2010]

Homework Statement

The top of a tower much like the leaning bell tower at Pisa, Italy, moves toward the south at an average rate of 1.4 mm/y. The tower is 59 m tall. In radians per second, what is the average angular speed of the tower's top about its base?

Homework Equations

ωavg=Δθ/Δt

The Attempt at a Solution

I first converted 1.4 mm/y :
1.4mm/y = (1m/1000mm) × (1y/365days) × (1day/24hr) × (1hr/60min) × (1min/60sec) = 4.4394E-11
Then, I divided the above answer by 59 m : (4.4394E-11)/59m = 7.5244E-13 rad/s but this wasn't correct. Where am I making my mistake? Thank you.

 

[kuruman]

Looks OK to me. I assume this is a computer-graded question. I see three possibilities (a) the formula that allows the machine to calculate the correct answer is incorrect, (b) you incorrectly entered the powers of 10 or (c) there is a problem with sig figs.