No, sscanf considers the leading zeros. But numbers are stored in double format in Matlab (and other programming languages as well), which does not consider leading zeros. They are useful for mathematical operations.
If you want to keep the leading zero, you treat the information as a string. Then use corresponding string methods for the manipulation:
val = '020550023 MBB'
s = strtok(s, ' ');
% Or:
index = find(~isstrprop(val, 'digit'), 1) - 1;
s = val(1:index);
