Answer
a) The pigeonhole principle states that if n pigeons are to go into m holes, such that n>m, then at least one hole must have more than one pigeon.
b) At least 2 number ends with the same digit.
Work Step by Step
a) The pigeonhole principle states that if n pigeons are to go into m holes, such that n>m, then at least one hole must have more than one pigeon.
b) The last digit of any number has to one of these 10: 0,1,2,3,4,5,6,7,8,9. So if we match 11 numbers then at least 2 of them must have the same last digit.
