The manner of denoting numbers in the decimal system is often referred to as decimal notation."Decimal" may also refer specifically to the digits after the decimal separator, such as in" 3.14 is the estimation of π to two decimals". The Egyptian hieratic numerals, the Greek alphabet numerals, the Hebrew alphabet numerals, the Roman numerals, the Chinese numerals and early Indian Brahmi numerals are all non-positional decimal systems, and need large numbers of symbols. Egyptian hieroglyphs, in evidence since around 3000 BCE, used a purely decimal system, as make the Cretan hieroglyphs (c. 1625−1500 BCE) of the Minoans whose numerals are closely based on the Egyptian model. Some non-mathematical ancient texts like the Vedas, dating back to 1900–1700 BCE make purpose of decimals and mathematical decimal fractions.

COMING SOON!

```
/*
* convert from any base to decimal
*/
#include <stdio.h>
#include <ctype.h>
int main(void) {
int base, i, j;
char number[100];
unsigned long decimal = 0;
printf("Enter the base: ");
scanf("%d", &base);
printf("Enter the number: ");
scanf("%s", &number[0]);
for (i = 0; number[i] != '\0'; i++) {
if (isdigit(number[i]))
number[i] -= '0';
else if (isupper(number[i]))
number[i] -= 'A' - 10;
else if (islower(number[i]))
number[i] -= 'a' - 10;
else
number[i] = base + 1;
if (number[i] >= base){
printf("invalid number\n");
return 0;
}
}
for (j = 0; j < i; j++) {
decimal *= base;
decimal += number[j];
}
printf("%lu\n", decimal);
}
```