I need help making an equation.

I have a range of numbers, e.g. 1.009-1.059,1.060-1.020.....
I beleive I need an IF THEN equation. If a number falls in the range
between e.g. 1.009 and 1.059, I have get the value, e.g. 5, if the number
fall between 1.060 and 1.020 I get the value 6. This pattern could continue
forever.

Can anyone help?

Thanks