If 14 February 2001 was a Wednesday, then what day of the week will be 14 February 2101 (i.e., after a century) ? 

If 14 February 2001 – Wednesday

14 + 3 + 0 + 0 + 0 + 0 = 17

$\frac{17}{7}$remainder 3 Wednesday

Then 14 February 2101

14 + 3 + 5 + 0 + 0 + 0 =22

$\frac{22}{7}$ = 1 remainder - Monday