Arithmetic with char and long

I ran into a cast type problem which i do not quite know how to
approach, please help.

I have a float variable s initialized to 0. in a loop i use following
code:
s=s+(float)score[tmp1];

score is a char array. this array contains numbers 1-5.
it seems that every time loop executes s is increased by about 50,
increases range from 48 to 53 ish.
 without the cast i get exactly same behavior.
I can verify that values in s are ranging from 1 to 5 with print
statement using %c in the print.

Full loop is below, score is a global variable.

================start paste==================
while(i1<ML[movie][1]){


			weight=weight+1;
			tmp1=i1+ML[movie][0];
		s=s+(float)score[tmp1];
		printf("score in loop is: %c",score[tmp1]);
		printf("s is: %f\n",s);
			i2++;

		i1++;
	}

================end paste=================

sorry cant post full code, its rather long and to run requires a
rather large pre-formatted dataset in same dir.

Thanks ahead for ur help.