Read the row of digits below from left to right.
4 5 2 7 3 8 1 6 3 9 0 4 4 5 6 2 8 1 7 3 6 2 9 5
Take every two neighbouring digits of the row as a pair (1st and 2nd, 2nd and 3rd, and so on). How many of these pairs add up to 9?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 8
Each digit and the digit just after it form a pair, so the pairs are neighbours in the row. Going from left to right, every pair is added; the pairs whose sum is 9 are:
4, 5 (1st and 2nd digits)
2, 7 (3rd and 4th digits)
8, 1 (6th and 7th digits)
6, 3 (8th and 9th digits)
9, 0 (10th and 11th digits)
4, 5 (13th and 14th digits)
8, 1 (17th and 18th digits)
3, 6 (20th and 21st digits)
Every other neighbouring pair adds up to a number other than 9.
So the answer is 8.