'Number Play' — Practice

Question 1

Is 1221 a palindrome? What about 1232?

Accepted Answer

1221 is a palindrome (reads same forwards and backwards). 1232 is NOT a palindrome (forwards: 1232, backwards: 2321 — different).

Question 2

Find the digit sum of 9,99,999.

Accepted Answer

9+9+9+9+9+9 = 54 → 5+4 = 9. The digit sum is 9.

Question 3

Apply the Kaprekar routine to 1000 and count the steps to 6174.

Accepted Answer

1000 → 1000−0001=0999 → 9990−0999=8991 → 9981−1899=8082 → 8820−0288=8532 → 8532−2358=6174. Total: 5 steps.

Question 4

In a 3×3 grid, the centre cell has value 50. Its 8 neighbours are 45, 48, 42, 55, 40, 38, 52, 47. Is the centre a supercell?

Accepted Answer

No, because 52 and 55 are greater than 50.

Practice — 'Number Play'