The post office sold 900 stamps yesterday. 1/4 of the stamps are postcard stamps. How many postcard stamps did they sell?

1/4 =.25 or 25%

a (postcard stamps) =.25 (percentage of postcard stamps) * 900 (total of stamps)

900 *.25 = 225

They sold 225 postcard stamps

To check:

225 * 4 = 900

Hello! To solve this problem you can convert 1/4 into a decimal (0.25), and then multiply that decimal by 900. You multiply the two because 25% (1/4) percent of the stamps are postcard stamps, thus by doing so you're able to determine how many of the stamps were postcard stamps. You should get an answer of 225 stamps.