Formatting a number with a metric prefix (SI style)

I'm looking for an existing solution, for converting a number with a metric suffix (SI style) to float or int.

Additionally, my initial number with a metric suffix is a string.

Example:

I have:

a = "1u"b = "2m"c = "1.1u"

I want:

a = 0.000001b = 0.002c = 0.0000011