The bar model is a visual representation of a number using unit cubes, as stated on SplashMath.com. One cube is equal to one. One line is equal to 10 cubes. One sheet is equal to 100 cubes or 10 lines.
The bar model is typically used in elementary level math as a pictorial approach to solving addition and subtraction problems. The bar model helps students visualize the difference between the numbers given and the amount they are looking for in a word problem. The model starts with addition and subtraction, but can be expanded to more difficult elementary level problems such as multiplication, division, fractions, ratios and percents.