5. Find the least common multiple (lcm) of the pairs of integers given in exercises 4. These were:
a). a=1,575 and b=231
b). a = -3719, b = 8416
c). a = 28,844, b = -15,712
6. Find the prime numbers less than or equal to the following natural numbers.
a) less than 200
b) less than 500
7. Find a (mod n) in each of the following cases.
a) a = 43,197, n = 39
b) a = -125,617, n = 315
8. Find a solution in each of the following congruencies
a) x = 7 (mod 9)
b) x = 4 (mod 12)
c) x = 16 (mod 21)