How many items in the product (a1 + A2 + a3) (B1 + B2 + B3) (C1 + C2 + C3 + C4 + C5) after expansion The counting principle of classified addition and the counting principle of distributed multiplication in senior two

How many items in the product (a1 + A2 + a3) (B1 + B2 + B3) (C1 + C2 + C3 + C4 + C5) after expansion The counting principle of classified addition and the counting principle of distributed multiplication in senior two

3 * 3 * 5 = 45 items