Question
What are the missing numbers?
7721, (a)          , 7801, 7841, (b)          , 7921
2 m
(a)

Click button first when a symbol is required. X

(b)

Click button first when a symbol is required. X

What are the missing numbers?
7721, (a)          , 7801, 7841, (b)          , 7921