Question

Numbers in circles follow the pattern shown below. In which horizontal row of circles does the number 1001 first appear?

Answer 1

1001 is a multiple of 7,11 & 13 [ 1001 = 7*11*13 ]
We have to choose the biggest factor here as it will be the one which will get us to our number the fastest or in other words in the least amount of steps.
So at row number 13, we will start the first steps in getting to 1001.
Since 1001/13 = 77
We can easily get that at row 13 + (77 - 1) = 89 we will see 1001 for the first time.