Most of these questions involve work on length and perimeter which we have not covered yet this year, but you did in Year 3. Just a reminder for you:

1cm = 10mm

1m = 100cm  

To convert cm to mm you need to multiply by 10   eg  4 cm = 40mm

To convert mm to cm you need to divide by 10 eg 120mm = 12 cm

To convert m to cm you need to multply by 100    eg 3m = 300cm

To convert cm to m you need to divide by 100 eg  1000cm = 10 m

Perimeter is the distance all the way around the outside of a shape.