Big number multiplication gets stupid simple with this hack. Add a zero, then subtract the original number—a two-step process anyone can master without breaking a sweat.

Here's how to use Excel as a calculator to perform basic arithmetic operations such as addition, subtraction, multiplication, and division.

Abacus Tricks for Fast Mental Math (With Examples) The abacus is more than just a counting tool; it's a powerful brain development instrument. Learning abacus involves visualizing bead movements ...

All you need to do is turn a subtraction or division problem into an addition or multiplication problem before performing this trick. Or you could just use a calculator.

This illustrated pamphlet describes the operation of manual and electrically operated versions of the Underwood Sundstrand printing adding machine. Addition, subtraction, and multiplication by ...