$$\left({\frac{\left({\mathtt{2.99}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{{\mathtt{6}}}\right)}{{\mathtt{44.892}}}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{146.04}} = {\mathtt{66\,750.334\: \!751\: \!848\: \!881\: \!760\: \!7}}$$
Well the first three digits are 667 (the next one 5 is used for rounding if it is 5 or bigger the the third one goes up) so now we have
668 but 668 is much smaller than 66 750 we can't have that. We need some zeros but they are not significant.
So the answer is
66,800