A dress marked $52.00 has a discount of 20%. How much is the discount?

a. $13.00

b. $41.60

c. $10.40

d. $12.00

Mentally: 10% of $52 is $5.20 so 20% is twice as much or $10.40 (Answer c)

To find 10% of a number just move the decimal one place to the left and to find 20% simply double the answer you got when you found 10%.

Computational way: 20% of $52 =.2 x 52 = 10.4 which in money is $10.40