Give this a shot
If you can count to 16 that's all you need to start with.
Find a ruler/tape that is setup with 16 marks per.inch take a hard look at it.
If you count over from the left side to the right and count the small marks till you get to 8 , that will be 1/2" now if you do the same count over 4 marks that will be 1/4" the same thing ,count over 2 marks and that would be 1/8" you must do just a bit of math in your head... 8 - 16th div. by 2 = 4 - 8th, so to say if you look at the ruler and one end of the ruler is on the edge and you want to cut the board at 1 1 /8" you would count over from the 1 " mark and count the 2 1/16th marks to the right on the ruler, this will give you 1 1/8 " ,lets say you want to mark and cut the board at 1 1/4" you would do the same thing but this time count over 4 marks, this will give you 1 1/4" ,this is true for all rulers, it can be marked in 32 marks to a inch or 64 marks to the inch, the unit is always 1" or to say the hole unit is always 1" ,,, so to say if you want to mark the board at 1 16/32 you would count over from the 1 inch mark and count 16 little marks on the ruler and you would be set at 1 1/2" , 16 marks is 1/2 of the unit in the 32nd scale///
Using the 1/16" inch scale ▼
I should note*** the end of the ruler/edge is always " 0 " and the " 1 or the 2, etc. " is the same, lets say you need to mark the board at 3 3/16" , you would go to the 3" inch mark on the ruler and count over 3 marks on the ruler, this would be the spot you need to mark the board..
for the cut..
Let's do one more so you get it , say you need to mark the board at 3 3/8", you would go to the 3" mark on the ruler and count 6 marks to the right,this would be 3 and 6 /16 (3/8") ,,because you know the next mark would be 7/16".
The only time you need to change the call is when the top number can be div. by 2,,,all other calls stay the same like 5/16,7/16,9/16,13/16,15/16, once you hit the 16/16 the call will move by " 1" that's to say 3 16/16 would be 4"...inchs....then you start all over again...
Think of it as money, one dollar is one unit, it takes 4 parts to make one unit ,or to say 25 cents is one 4th of the unit...(of the hole) if it was on a ruler the ruler would have 4 marks per. inch...
Hope this helps...