①

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

int main()
{
	for (int i = 1; i <= 9; i++)
	{
		for (int j = 1; j <= i; j++)
	{
			printf("%d*%d=%d\t", j, i, i * j);
	}
	printf("\n");
	}
	return 0;
}

②

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

int main()
{
	for (int i = 1; i <= 9; i++)
	{
		for (int j = i; j <= 9; j++)
	{
			printf("%d*%d=%d\t", j, i, i * j);
	}
	printf("\n");
	}
	return 0;
}