* Know the conversion: 1 liter (L) = 1000 milliliters (ml)

* Set up a proportion:

* (630 ml) / (1 L) = (x) / (1000 ml)

* Solve for x:

* Cross-multiply: 630 ml * 1000 ml = x * 1 L

* Simplify: 630000 = x

* Therefore, x = 630000 ml

* Convert back to liters: 630000 ml / 1000 ml/L = 630 L

Answer: 630 ml is 63/100 or 0.63 of 1 liter.