C++ header file header file (library) The c++ header file declares a set of functions

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C++ <cmath><math.h> header file
<iomanip> header file (library)
The c++ <cmath> header file declares a set of functions to
perform mathematical operations such as sqrt() to calculate the
square root, log0
to find the natural logarithm of a number etc.
the program should reduce from 9 decimal to 2 decimal
1. Manually 9 decimal
2. Program 2 decimal