Slide rule
Drag point C' to move the upper rule. There is a point to move the hairline cursor.
Move the drawing pad and/or zoom out (these tools are on the rightmost button) if the whole slide rule won't fit on your screen.
To multiply (4x2, for example):
Move the upper slide so that 1 is above 4.
Move the hairline to align with 2 on the upper slide.
Read down the hairline for the product.
Susan Addington, Created with GeoGebra |