1230 dm is bigger.
1 meter = 100 cm = 1000 mm there are 10 mm in 1cm so 300 mm = 30 cm. greater
300mm is 11.811 inches.
300 mm is equal to 30 cm, so 300 mm would be greater.
300mm is 9.72 x 10-18 parsecs.
32cm (8 sides x 4cm = 32cm)
450mm x 300mm 45cm x30cm 1350cm
A 300mm lens is a telephoto lens, which will magnify the subject. It used to be that a 300mm lens was actually 300mm long, but with the use of compound lenses, they can be shorter, but have a "virtual" length of 300mm. On a 35mm camera, about 50mm is the "natural" lens size -- most cameras come with a 50mm lens. You can divide 300mm by 50mm to find out how much it magnifies from the "natural" position. 300/50 = 6, so it will magnify 6 times.
32 centimeters is 320 millimeters.