Question

(1) 7, 4, 2, 9...
(ii) 0, 1,8
3. Write the greatest 4-digit number using different digits with 7 at hundreds place.
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Answer 1

your question is not very evident, it is pretty vague. so i answer it like how i understood.

1. 9742

2. 810

3. 9799

i have arranged all the numbers in its greatest possible value.

hope it helps.