Answer:
19×21 = 399
Explanation:
You want the least positive multiple of 21 that is greater than 380.
Ceiling
Let n be the multiplier. Then you want the smallest integer n that satisfies ...
21n > 380
n > 18 2/21
The least integer greater than 380/21 = 18 2/21 is 19.
Multiple
The 19th multiple of 21 is 19×21 = 399.
The least positive multiple of 21 greater than 380 is 399.