Divisibilityhard
0:00.0

To test if a large base-10 integer NN is divisible by 101, a mathematician groups the digits of NN from right to left into two-digit blocks: B0,B1,B2,B_0, B_1, B_2, \dots. Which of the following operations on these blocks yields a result that is congruent to N(mod101)N \pmod{101}?