I am sure we are well aware that computers and electronic devices might not work after SHTF.

I took some time to decide to post this thread here in Home School rather than other areas, as probably we will have more pertinent replies here given the subject matter.

Recently I thought about how tough it would be just to do mathematics the MANUAL way, without calculators.

Mathematics are crucial. We will need to use **arithmetic** and some trigonometry to build basic structures, calculating how much wood we need, how long ropes have to be, etc.

I have used basic **trigonometry** to calculate things, remembering my **SOH CAH TOA** from high school, but of course I always had a calculator to do the Sine, Cosine, etc.

Just in the past couple of days I was thinking about **Pythagoras’ Theorem**, and how useful it is. Right-angled triangles are very common in construction. But to use it requires calculating **square roots**.

So, I don’t remember if I ever learned how to do square roots (such a “simple” thing that most basic calculators have!) by hand, so I Googled around.

Now, I got to here:

http://www.homeschoolmath.net/teaching/square-root-algorithm.php

The method seems straightforward enough but I still got quite stuck with it and got the wrong answer (I checked it with a calculator). I am no dumb-dumb (I “reinvented” a method to calculate something else the other night and I was happy that my brain and basic **algebra** still worked pretty good) but I still could not really follow this manual method.

My question is, what other manual methods do you guys think we should “prepare” for? i.e., get printed documentation for the methods.

A booklet of tables of **logarithms** has always been something I kept in mind. I did get a **SLIDE RULE** and even researched how to use an **ABACUS** as a backup, with printed pages on how to use them, but there are quite a few other things we should think about right now with the convenience of the Internet and calculators, laser printers, etc. on hand at the moment.

PS – One other thing is, I take it for granted that I still know how to calculate long division and other such arithmetic by hand, but I am not so sure the younger generation knows how to do it!!!

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