Numbers entered with a backtick ` but without a specified precision are treated as machine precision numbers, which is to say, they are treated just like an undecorated number with a decimal point. A backtick without a number specifying precision is useful when applied to an integer without a decimal point. With a number having a decimal point, the backtick does nothing.
You can determine the precision of a number using the Precision
function:
In[1]:= Precision[70.6]
Out[1]= MachinePrecision
In[2]:= Precision[70.6`]
Out[2]= MachinePrecision
The symbol MachinePrecision
is treated as a constant and is set to the value of $MachinePrecision
, which begs the question, "What is $MachinePrecision
?" From the documentation:
The typical arrangement is that all machine?precision numbers in the Wolfram Language are represented as "double?precision floating?point numbers" in the underlying computer system. On most current computers, such numbers contain a total of 64 binary bits, typically yielding 16 decimal digits of mantissa.