The sum of the digits of the perfect square nearest to 59678 is:
2019
The sum of the digits of the perfect square nearest to 59678 is:
- A.
22
- B.
26
- C.
24
- D.
28
Attempted by 112 students.
Show answer & explanation
Correct answer: D
Concept
The perfect square nearest to a number N is found by taking the square root of N, rounding to the nearest integer k, and comparing the two candidate squares k2 and (k±1)2. The one with the smaller absolute distance from N is the nearest perfect square.
Application
Estimate the square root: √59678 ≈ 244.3, so the candidate integers are 244 and 245.
Compute 2442 = 59536, with distance |59678 − 59536| = 142.
Compute 2452 = 60025, with distance |60025 − 59678| = 347.
Since 142 < 347, the nearest perfect square is 59536.
Add its digits: 5 + 9 + 5 + 3 + 6 = 28.
Cross-check
244 and 245 are consecutive integers whose squares bracket 59678, so no other integer square can be closer. The smaller distance (142) confirms the lower square is nearest, giving a digit sum of 28.