There are many types of units in use in the world. For example, distance can be reported in meters, kilometers, feet, inches, etc. The agreed symbols and the units to be used are intended to clarify the situation. Table 1 shows the seven basic units of the SI system. All other units are based on these. This section focuses on the most common units in use in Finland and their multiples. Of the units in Table 1, these are length (distance), mass, and time.[br][br]World is full of examples, where things have not gone smoothly because of units. For that reason, all calculations should be done with units in SI-system. Unfortunately, not all countries use SI-system.[br][br][color=#0000ff]If you are not familiar with SI-system, use time to learn it. [/color][br]

For example, the area of a rectangle is calculated by the formula page length times the length of the second page. Since lengths are given in meters, the unit of area becomes one meter to another, or square meter (m[sup]2[/sup]). In a similar way, a cubic metre (m[sup]3[/sup]) is obtained for the volume of the rectangular prism. On the other hand in cooking and baking, the volumes are given by means of decilitres and litres. In the technical field, a volumetric flow is also easily given in the form of litres per minute. Since the litre is not a basic unit, then it must be converted into cubic meters for calculations. This change is made by a ratio[br] [br] [br][math]\large 1 \;l = 1\; dm^3.[/math][br] [br]The units used are industry-bound. In medications, for example, are used millimitres (ml) or milligrams (mg). In brewing, it is more common to talk about hectolitres (hl).[br][br]