Standard units are defined in SI-system. For example, the standard unit for a mass is one kilogram. When we are talking about the mass of a spider, kilogram as a unit is exaggerated. On the other hand, the measures of a box are usually given in centimetres but the volume in litres. [br][br]In this part, we discuss about SI- system and unit transformation. [br][br]SI-prefixes can be used to express the magnitude to the standard unit. For example,[br][br]  [math]\LARGE 1\text{ km}=1\cdot 10^3 \text{ m}=1000\text{ m}\\[br]\LARGE 1\text{ cm} = 1\cdot 10^{-2}\text{ m}=0.01 \text{ m}[/math][br] [br][br]When volume is solved in metrics but the result must be informed in litres (context!), we can use the information[br][br]  [math]\LARGE \textcolor{blue}{1\text{ }\cal l=1\text{ dm}^3.}[/math]

[u]Lengths:[/u][br][math]\Large 1\text{ m}=1\cdot 10^{0-(-2)}\text{ cm}=1\cdot 10^2\text{ cm}=100\text{ cm}\\[br]\Large 2.3\text{ cm}=2.3\cdot 10^{-2-0}\text{ m}=2.3\cdot 0.01 \text{ m}=0.023 \text{ m}\\[br]\Large 0.5\text{ km}=0.5\cdot 10^{3-(-1)}\text{ m}=0.5\cdot 10^4 \text{ m}=5000 \text{ dm}[/math][br][br][u]Area:[/u][br][br][math]\Large 1\text{ m}^2=1\cdot (10^{0-(-2)}\text{ cm})^2=1\cdot (10^2)^2\text{ cm}^2=10^4\text{ cm}^2=10000\text{ cm}^2\\[br]\Large 0.01\text{ ha}=0.01\cdot (10^{2-0}\text{ m})^2=0.01\cdot 10^4 \text{ m}^2=1\cdot 10^2 \text{ m}^2=100\text{ m}^2\\[br]\Large 4.7\text{ dm}^2=4.7\cdot (10^{-1-(-2)}\text{ cm})^2=4.7\cdot 10^2 \text{ cm}^2=470\text{ cm}^2[/math][br][br][u]Volume:[/u][br][br][math]\Large 1\text{ m}^3=1\cdot (10^{0-(-1)}\text{ dm})^3=1\cdot (10^1)^3\text{ dm}^3=10^3\text{ dm}^3=1000\text{ dm}^3=1\text{ }\cal l\\[br]\Large 2\text{ }\cal l=2 \text{ dm}^3=2\cdot (10^{0-1}\text{ m})^3=2\cdot 10^{-3} \text{ m}^3=2\cdot 0.001\text{ m}^3=0.002\text{ m}^3\\[br]\Large 5.2\text{ dl}=5.2\cdot 10^{-1-(-3)}\text{ ml}=5.2\cdot 10^2 \text{ ml}=520\text{ ml}\\[br]\Large 3.1\text{ dl}=0.31 \text{ }\cal l=0.31 \text{ dm}^3=0.31\cdot 1000 \text{ cm}^3=310\text{ cm}^3[br][br][/math]

[b]Calories[/b] is and old unit for enerqy and it is originally a latin word meaning [i]temperature[/i]. [sup][url=https://fi.wikipedia.org/wiki/Kalori#cite_note-2][/url][/sup] It is used as unit of thermal energy. It is not officially used any more as joule is the unit SI system. However, it is commonly used to inform, how much the energy is formed when the food is burned. In spoken language we wrongly use the plain calories instead of [b]kilocalories [/b](1 kcal = 1000 cal).[br][br]In tranformation, 1 cal = 4.1868 J or 1 J = 0.239 cal (rough).[br][sup][url=https://fi.wikipedia.org/wiki/Kalori#cite_note-5][/url][/sup]

Measures used in recipes do not usually follow SI system. Here are most common ones:[br][br][list][*] 1 dl = 7 tblsp = 7 rkl (in Finnish)[/*][br][*] 1 tblsp = 3 tsp = 3 tl[/*][br][*] 1 tsp = 5 ml[/*][br][*] 1 ml = 1 mm (maustemitta) [/*][br][*] 1 US cup = 240 ml [/*][br][*] 1 UK cup = 280 ml[/*][br][*] 1 kkp (Finnish cup) = 150 ml[/*][br][*] dozen = 12 (tusina)[/*][br][*] 1 stick = 113 g[/*][br][*] 1 dl = 65 g of cake flour[/*][/list][br][br]As you can see, there are lot of differences in measures. For example, one cup differs in Finland, USA and UK. You can find more of these measures in [url=http://www.maku.fi/artikkelit/mitat-ja-muunnokset]www.maku.fi [/url] (in Finnish).[br]