2^ 100=2×2^99=2×(2^3)^33=2×8^33

=2×(7+ 1)^33=2[7^33+......+33*7+ 1)

In parentheses, only the last term 1 is not a multiple of 7.

So the remainder of 2 divided by 7 to the power of 100 is 2× 1=2.

Today is Sunday, 100 days later 2, what day is it today?