Question

abcd+abc+ab+a=1995,求a+b+c+d=?

如上

Answer 1

用程序算的。
#include <stdio.h>

void main()
{
int a = 1, b, c,d;
for (b= 0;b<=9;b++)
{
for (c = 0 ; c <=9;c++)
{
for (d=0;d<=9;d++)
{
if ((a*1000+b*100+c*10+d) + (a*100+b*10+c) + (a*10 + b) + a == 1995)
{
printf("a = %d\nb = %d\nc = %d\nd = %d\na + b + c + d = %d\n",a,b,c,d,a + b + c + d);
}
}
}
}

}

最后算出 a=1 b=7 c=9 d=8 a+b+c+d = 25

Answer 2

1995/3=665-1=664
664/8=83-1=82
82/2=41-1=40
40/8=5-1=4
a=3 b=8 c=2 d=40