a)
BCNN(9,72,108)
9 = $3^{2}$
72 = $2^{3}$ . $3^{2}$
108 = $2^{2}$ . $3^{3}$
BCNN(9,72,108) = $2^{3}$ . $3^{3}$ = 216
⇒ BCNN(9,72,108) = 216
b)
ƯCLN(180; 240,08)
180 = $2^{2}$ . $3^{2}$ . 5
240 = $2^{4}$ . 3 . 5
8 = $2^{3}$
UCLN(180, 240, 8) = $2^{3}$ = 8
⇒ UCLN(180, 240, 08) = 8