Resistance

[Weather Freak]

Hello, I am stumped on this question from my text book:

A calculator is rated at 0.10 W when connected to a 1.50 V battery. What is the resistance of this device?

I tried by using this equation which I felt should work:

(delta V)^2/R=P

But it doesn't seem to get me the correct answer (which is 22 ohms). Any ideas? Thanks!

[ShawnD]

P = \frac{V^2}{R}

R = \frac{V^2}{P}

R = \frac{1.5^2}{0.1}

R = 22.5 \Omega

Maybe the book is just wrong.

[Weather Freak]

Thank you very much! Yeah... the 22 answer probably has something to do with sig figs.