How do you say 5-20-10 in Spanish?

There's no single way to say "5-20-10" in Spanish because it depends on the context. Here are a few possibilities:

* As a date: If it's a date (May 20th, 2010), you'd say "20 de mayo de 2010" (Note that Spanish date order is day-month-year).

* As a code or sequence: If it's a code or a sequence of numbers, you would simply say "cinco, veinte, diez" (five, twenty, ten).

* As a measurement: Depending on the unit, it could be translated differently. For instance, if it represents 5 meters, 20 centimeters, and 10 millimeters, a more natural way to express that might be "5 metros, 20 centímetros y 10 milímetros".

To get the best translation, you need to provide the context.