I’m taking physics and this is very confusing to me any help?

Just conversion of units

Explanation:

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(Kilo, Hecto, Deca, Base, Deci, Centi, Milli, Micro)

First one is decaliter which is 10 liters so I convert to liters first 0.0007 liters and then add another 0 to make it in daL so 0.00007

Second is converting from meters to millimeters so 1000mm go into one meter so 3100mm

Same thing for the mass one 0.3kg to g well there is 1000g/1kg and then the kg cancel out (this is the safest way to do this) and you get 300 grams

The last one is cm to decimeters not deca and there are 10 centimeters in each decimeters or you could convert to meters and then back again. I would just take the easy out and go with 25.4cm (I think of this one like mm to cm as it is the same ratio and how many times have you used a ruler with both units on it. A 30 cm ruler would be 3 decimeters for the whole 30 cm.

an obstruction