Hey my math works if you are willing to forget Log rules in math. Like since 2^n=4.....then n=2

Therefore, 2^n=10.....n=5 since before 2*2=4 then 2*5=10. It has to be.

But hey lets try it the right way and 2^n=10....n=3.32.., then from a HVL of 0.25in you get 0.83in. approximately for a TVL of lead for Cs-137.

TVL for Tungsten becomes 0.53in fir Cs-137.

Luckily for me I dont have to admit to error due to my disclaimer in my post

Reminds me of a story. NASA buillds a rocket (I believe to orbit some distant planet or something like that)and they have one set of enginneers calculate one set of numbers and give said numbers to another group of engineers. But, since none of them had attended Naval Nuclear Power School and missed points on a test for their mistake, their math made them "Unitless" men in their work. So they missed their mark and found out one group used english units the other thought they were in metric. They probably are still out there looking for their "unit"....of measurement of course....and a new job.