prime between number of 1234 to 1352 are 1237, 1249, 1259, 1277, 1279, 1283, 1289, 1291, 1297, 1301, 1303, 1307, 1319, 1321, 1327
You would multiply the orignial price by (10%) converted to decimal to find the discount:
21 * 0.10
=2.10
Then, you subract the discount from the original price to see how much he paid:
21 - 2.10 = $18.90
