The unit digit of 47² is:
A{'text': '3'}
B{'text': '6'}
C{'text': '9'}
D{'text': '1'}
Answer & Solution
Correct answer: C. {'text': '9'}
1. The unit digit of a square is determined by the unit digit of the base.
2. Unit digit of 47 is 7; 7 × 7 = 49 → unit digit 9.
3. Verification: 47² = 2209, which ends in 9 ✓.
4. Hence the unit digit is **9**.
_Source: Selina Concise ICSE Class 8 Mathematics Ch 3 "Squares and Square Roots", Unit digit rules_
Related questions
A right triangle has hypotenuse 5 cm and one side 3 cm. The third side squared is:90 = 2 x 3 x 3 x 5. Since 2 and 5 are unpaired, 90 is:The square root of 6400 is:48 = 2x2x2x2x3 has one unpaired 3. The smallest number to multiply 48 by to get a perfect 256 = 2x2x2x2x2x2x2x2. Pairing the factors, its square root is:Subtracting 1, 3, 5, ... from 81 reaches 0 at the 9th step. So the square root of 81 is:A perfect square has two integral square roots; the root symbol denotes only the:Finding a number whose square is known is called finding the: