Convert Celsius to Fahrenheit with C language

#include <stdio.h>
int main()
{
    double celsius, fahrenheit;
    printf("\nEnter Temperature in Celsius : ");
    scanf("%lf", &celsius);
    /*fahrenheit = (9/5*celsius)=32 */
    fahrenheit = (1.8 * celsius) + 32;
    printf("\nTemperature in Fahrenheit : %.2lf ", fahrenheit);
    return 0;
}

Enter Temperature in Celsius: 90

Temperature in Fahrenheit: 194.00