How many people own a suv?
a. 4
b. 42
c. 420
d. 4,200

For this, no math is even needed! The question says 1,000 people were interviewed. 42% percent of that 1,000 owns an SUV. If it's a percent, it is 42/100, right? Now we have to make that 42/100 out of 1000. We add a zero to the 100 on the bottom (42/1000). We do the same thing on the top. Add a zero! 420. 

SECOND POSSIBLE SOLUTION
Solve this with logic! 42% is nearly 50%. Half of 1,000 is 500. What is closest to 500? 420! This solution is even easier.

Hope this helps you!