Answer:
15
Step-by-step explanation:
Let's call the mystery number x.

Hope this helps!
You have to multiply and add!
Answer:
3.427 *10^3
Step-by-step explanation:
Move the decimal so there is one non-zero digit to the left of the decimal point. The number of decimal places you move will be the exponent on the 10
. If the decimal is being moved to the right, the exponent will be negative. If the decimal is being moved to the left, the exponent will be positive.
21.5m squared
i just multiplied them