Numbers & Arithmetic

This section covers the standard written methods for arithmetic on whole numbers and decimals. The Long Multiplication Calculator multiplies two numbers the way it is taught in school - one partial product per digit of the multiplier, with each carry and each place-value shift shown - and handles negative numbers and decimals in the same calculator.

Long multiplication works by breaking the multiplier into its place values: multiplying 214 by 36 is really 214 x 6 plus 214 x 30, and the second partial product is shifted one column left because the 3 stands for 30, not 3. Adding the shifted partial products gives the final answer. Decimals follow the same steps on the digits, and the decimal point is placed at the end by counting the total number of decimal places in the two inputs. The calculator shows each of these stages rather than collapsing them into one number.

The point is the method, not just the product: the step-by-step output lets a student follow exactly where each digit of the answer comes from. It runs in your browser and states the arithmetic at every stage. More written-method calculators - long division, addition and subtraction with carrying and borrowing - are planned for this section.