Strain Gage Bending

sean882
In strength of materials, we have to do a project using strain gages to measure a weight between 0 and 10 lbs with an accuracy of .1lbs. My group is using bending strain. We have a formula, S$$_{}b$$=$$\frac{F*L*6}{E*b*h}$$, where F is the weight applied, L is the length, E is the Young's Modulus, b and h are base and height dimensions, respectively. We need S$$_{}b$$ to equal between 500 and 1,000. Where does the 6 come from in the formula? We have a feeling it comes from moment of inertia formulas somehow, but could you explain how it is derived? Thanks,

-Sean