Question 1
Which of the following numbers are not perfect squares?
(i) 2032 (ii) 2048 (iii) 1027 (iv) 1089
- A perfect square is a number formed by multiplying an integer by itself (e.g., ).
- The unit digit of squares of digits to are:
- A perfect square can only end in or .
- Any number ending in or cannot be a perfect square.
(i) 2032
Step 1 · Check the Unit Digit of 2032
The unit digit of is .
Since a perfect square cannot end in , is not a perfect square.
(i) Not a perfect square
(ii) 2048
Step 1 · Check the Unit Digit of 2048
The unit digit of is .
Since a perfect square cannot end in , is not a perfect square.
(ii) Not a perfect square
(iii) 1027
Step 1 · Check the Unit Digit of 1027
The unit digit of is .
Since a perfect square cannot end in , is not a perfect square.
(iii) Not a perfect square
(iv) 1089
Step 1 · Verify if 1089 is a Perfect Square
The unit digit of is , so it can be a perfect square.
Since and , the square root must be between and .
A number ending in can have a square root ending in or , so the possibilities are or .
Testing :
Since , is a perfect square.
(iv) It is a perfect square ()
- Assuming all numbers ending in are perfect squares: A unit digit of only indicates that a number might be a square (e.g. ends in but is not a perfect square). Verification by calculation is necessary.
- Not remembering impossible unit digits: A number ending in or is guaranteed not to be a perfect square and can be ruled out immediately without factorization.
More questions in FIO
Which of the following numbers are not perfect squares?
(i) 2032 (ii) 2048 (iii) 1027 (iv) 1089
Which one among , , , has last digit 4?
Given , what is the value of ?
(i)
(ii)
(iii)
(iv)
(v)
Find the length of the side of a square whose area is .
Find the smallest square number that is divisible by each of the following numbers: 4, 9, and 10.
Find the smallest number by which 9408 must be multiplied so that the product is a perfect square. Find the square root of the product.
How many numbers lie between the squares of the following numbers?
(i) 16 and 17 (ii) 99 and 100
In the following pattern, fill in the missing numbers:
(a)
(b)
How many tiny squares are there in the following picture? Write the prime factorisation of the number of tiny squares.
Find the cube roots of and .
What number will you multiply by 1323 to make it a cube number?
State true or false. Explain your reasoning.
(i) The cube of any odd number is even.
(ii) There is no perfect cube that ends with 8.
(iii) The cube of a 2-digit number may be a 3-digit number.
(iv) The cube of a 2-digit number may have seven or more digits.
(v) Cube numbers have an odd number of factors.
You are told that is a perfect cube. Can you guess without factorisation what its cube root is? Similarly, guess the cube roots of , , and .
Which of the following is the greatest? Explain your reasoning.
(i)
(ii)
(iii)
(iv)