Of course you are right, the slide rule works with logarithmic scales that are “added” together to do multiplication. Linear scales could be used to add, but th

Of course you are right, the slide rule works with logarithmic scales that are “added” together to do multiplication. Linear scales could be used to add, but the low number of significant digits (no more than three on standard slide rules) meant that it wasn’t worth it, and no engineering slide rule that I ever saw had scales for addition.