Find the greatest common divisor of the following sets of numbers: $$(34, 25), (80, 45), (66, 52, 70)$$.
Development:
$$34=2\times17, \ \ \ \ 25=5^2$$
$$g.c.d.(34,25)=1$$ (They do not have common divisors but $$1$$.)
$$80=2^4\times5, \ \ \ \ 45=3^2\times5$$
$$g.c.d(80,45)=5$$
$$66=2\times3\times11, \ \ \ \ 52=2^2\times13, \ \ \ \ 70=2\times5\times6$$
$$g.c.d.(66,52,70)=2$$
Solution:
$$g.c.d. (34,25) = 1 \\ g.c.d. (80,45) = 5 \\ g.c.d. (66,52,70) = 2 $$