Given a=10, b=200, and c=3000, verify the commutative and associative properties for addition and multiplication.

$$10+200 = 200+10$$ $$210 = 210$$

The completed expression is $a+b = b+a$. The calculated value is $\boxed{210}$.

$$10 \times 200 = 200 \times 10$$ $$2000 = 2000$$

The completed expression is $a \times b = b \times a$. The calculated value is $\boxed{2000}$.

$$(10+200)+3000 = 10+(200+3000)$$ $$210+3000 = 10+3200$$ $$3210 = 3210$$

The completed expression is $(a+b)+c = a+(b+c)$. The calculated value is $\boxed{3210}$.

$$(10 \times 200) \times 3000 = 10 \times (200 \times 3000)$$ $$2000 \times 3000 = 10 \times 600000$$ $$6000000 = 6000000$$

The completed expression is $(a \times b) \times c = a \times (b \times c)$. The calculated value is $\boxed{6000000}$.

$$(10+200) \times 3000 = (10 \times 3000) + (200 \times 3000)$$ $$210 \times 3000 = 30000 + 600000$$ $$630000 = 630000$$

The completed expression is $(a+b) \times c = a \times c + b \times c$. The calculated value is $\boxed{630000}$.

$$10-10 = 0$$

The completed expression is $a-a = 0$. The calculated value is $\boxed{0}$.

$$3000 \times 1 = 3000$$

The completed expression is $c \times 1 = c$. The calculated value is $\boxed{3000}$.

$$200+0 = 200$$

The completed expression is $b+0 = b$. The calculated value is $\boxed{200}$.