Wednesday, September 22, 2010

Fast way to multiply a number by 7


/**
* @author Vijayan Srinivasan
* @since Sep 22, 2010 3:47:15 PM
*/
public class MulBy7 {

public static void main(String[] args) {
for(int i=0;i<10;i++){
System.out.print("i="+i+",");
int value=(i<<3)-i;
System.out.println("i*7="+value);
}
}

}


Output:

i=0,i*7=0
i=1,i*7=7
i=2,i*7=14
i=3,i*7=21
i=4,i*7=28
i=5,i*7=35
i=6,i*7=42
i=7,i*7=49
i=8,i*7=56
i=9,i*7=63