In a multiple choice test you rarely need the exact figure. When the options are far apart, a rounded estimate finds the right one in a few seconds and saves the calculator for close calls.
Round to one or two significant figures: 487 × 21 becomes 490 × 20 = 9,800, close to the exact 10,227. When you multiply, round one number up and the other down so the errors cancel: 487 × 21 becomes 500 × 20.
Check the size of the answer first. Wrong options are often out by a factor of 10, so know whether you're looking for hundreds or thousands before you read them. When two options are close, the last digit can settle it: 487 × 21 must end in 7, because 7 × 1 = 7.
Estimate, then look at the options. If two of them sit near your estimate, work that question out properly.