🧮 Math Calculators
Prosenttilaskuri, BMI, ikälaskuri ja roomalaiset numerot
Laske prosenttiosuudet — juomalaskuri, alennuslaskuri, prosenttikorotus ja paljon muuta.
Avaa työkalu →Laske tarkka ikäsi mistä tahansa syntymäpäivästä. Kuinka vanha olen tänään?
Avaa työkalu →Muunna numerot roomalaisiksi numeroiksi ja takaisin. Ilmainen roomalaisen numeron muunnin.
Avaa työkalu →Laske nopeus, matka tai aika kahdesta muusta arvosta. Ilmainen SDT-kolmiolaskuri.
Avaa työkalu →Yhteen-, vähennys-, kerto- ja jakolasku murtoluvuilla vaiheittain.
Avaa työkalu →Laske keskiarvosi kurssiarvosanoista ja opintopisteistä.
Avaa työkalu →Laske juomarahan määrä ja jaa lasku henkilöiden kesken.
Avaa työkalu →Muunna luvut sanoin sekkeille ja laskuille.
Avaa työkalu →Everyday arithmetic that is quicker to check than to do in your head — percentages, fractions, ratios of speed and distance, ages, tips, and numbers written out in words.
Each shows the working, which is the useful part. Percentage change in particular is a calculation most people can do and many get backwards, and seeing the expression makes the direction obvious.
Which tool do I want?
| If you… | Use |
|---|---|
| Percentage of, change between, or increase and decrease | Prosenttilaskuri |
| You need to simplify or convert a fraction | Murtolukulaskuri |
| Two of speed, distance and time are known | Nopeus, matka ja aika |
| You need an exact age or a duration in years | Ikälaskuri |
| You are splitting a bill | Juomarahalaskuri |
| You need a figure written out for a cheque or contract | Luku sanoin |
| You are converting Roman numerals | Roomalaiset numerot |
| You are working out a grade average | Keskiarvolaskuri |
A 20% fall does not undo a 20% rise
Percentages are taken from whatever the current value is, so the base moves. Take 100, add 20% to get 120, then remove 20% — that 20% is now of 120, so you lose 24 and land on 96. To get back to 100 you would need 16.7%.
The same asymmetry runs through anything measured in percentages. An investment down 50% needs 100% to recover. A price cut by 30% needs a 43% increase to return to where it was.
Related, and worth keeping separate: percentage points versus percent. An interest rate moving from 2% to 3% has risen by one percentage point and by 50 percent. Both are correct, they describe the same change, and choosing whichever sounds more dramatic is a standard trick in reporting.