sorry for asking many questions but im really bad at math sometimes?!

Answer:
Step-by-step explanation:
d = 10 mm
Circuference = πd
= 3.14 * 10 = 31.4 mm
When multiplying by 10,deimal point will move one step to your RHS.
Answer:
[tex]c = 31.4mm[/tex]
Step-by-step explanation:
[tex]c \: = \pi \: d \\ c = 3.14 \times 10 \\ c = 31.4mm[/tex]