# Deflection problem confusing units?

Everytime I try this question I keep getting 93.75 mm. I was just wondering where I'm going wrong. Here's my work:

$$BC=\dfrac{FL}{AE}=\dfrac{1500000\text{ N}\cdot 1250\text{ mm}}{100000\text{ mm}^2*200\text{ MPa}}=93.75\text{ mm}$$ For deflection to be in $\text{mm}$, all units have to be in $\text{N}$ and $\text{mm}$, right?

You are correct. The book probably meant $E = 200\text{ GPa}$, which is frequently adopted for steel.
You're probably aware of this, but just to make it explicit: your math only worked because $200\text{ MPa} = 200\text{ N/mm}^2$.