#include <stdio.h> #include <math.h> int main() { double p_factorial = 1; int max_itr = 21; for (int p = 1; p <= max_itr; p++) p_factorial *= p; double sum = 0; for (int p = max_itr; p >= 0; p--) { sum += 1/p_factorial; p_factorial /= p; } printf("sum= %.20f\n", sum); printf(" e = %.20f\n", M_E); printf("|sum-e|=%e\n", fabs(sum-M_E)); return 0; }