It's sometimes, because let's say I have 4/5 right? So when in a percent it's 80%. I suppose you could turn it into a a decimal of 80/100 but no not always. 3295729357/1000000000000. That doesn't have a denominator of 100, so yeah.
To find the area of a triangle, multiply the base by the height, and then divide by 2. The division by 2 comes from the fact that a parallelogram can be divided into 2 triangles.
