4-3

4-3.c

#include <stdio.h>

int main(){

	float vertically, horizontally;
	float inch = 2.54;
	float ans;

	printf("まずは横の入力\n");
	scanf("%f",&vertically);
	printf("よしよし、次は縦の入力\n");
	scanf("%f",&horizontally);

	vertically *= inch;
	horizontally *= inch;

	ans = vertically * horizontally;

	printf("面積は%05f cm^2だよー\n", ans);
	return 0;
}

単位はしっかり書こう！
(俺も忘れてたけどw)

了解w