Go gotcha: Numbers that start with zero

What's going on with the counting in this example?

const (
        Century = 100
        Decade  = 010
        Year    = 001
)
// The world's oldest person, Emma Morano, lived for a century,
// two decades and two years.
fmt.Println("She was", Century+2*Decade+2*Year, "years old.")

She was 118 years old.