Rational Numbers | FIO

Question 9

How many tiny squares are there in the following picture? Write the prime factorisation of the number of tiny squares.

Question diagram 1
Check your answer with HomiSolve it yourself, then let Homi check your steps and spot mistakes.
Solution

We need to count the total number of tiny squares and then find its prime factorization.

Step 1 — Counting the big squares

First, let us count how many big squares are arranged in the picture. We can count the number of big squares in each row and each column.

Number of big squares in a row = 9

Number of big squares in a column = 9

To find the total number of big squares, we multiply the number of rows by the number of columns.

Total number of big squares = Number of rows ×\times Number of columns

=9×9= 9 \times 9

81\boxed{81}

Diagram 1

Step 2 — Counting tiny squares in one big square

Next, let us look closely at one of the big squares. Each big square is made up of many tiny squares. We count the tiny squares along one side of a big square.

Number of tiny squares along one side of a big square = 5

Since each big square is a grid, the total tiny squares in one big square is 5×55 \times 5.

Number of tiny squares in each big square = 5×55 \times 5

=25= 25

25\boxed{25}

Step 3 — Calculating total tiny squares

Now, we can find the total number of tiny squares in the entire picture. We multiply the total number of big squares by the number of tiny squares in each big square.

Total tiny squares = Total number of big squares ×\times Number of tiny squares in each big square

=81×25= 81 \times 25

=2025= 2025

2025\boxed{2025}

Step 4 — Prime factorization of the total tiny squares

Prime factorization is breaking down a number into its prime factors (numbers only divisible by 1 and themselves). We will find the prime factors of 2025.

We start by dividing 2025 by the smallest prime numbers. Since 2025 ends in 5, it is divisible by 5.

2025÷5=4052025 \div 5 = 405

405÷5=81405 \div 5 = 81

Now we need to factorize 81. We know that 81=9×981 = 9 \times 9. Since 9 is 3×33 \times 3, we can write 81 as 3×3×3×33 \times 3 \times 3 \times 3.

So, the prime factors of 2025 are 5, 5, 3, 3, 3, 3. We can write this using exponents.

Prime factorization of 2025 = 3×3×3×3×5×53 \times 3 \times 3 \times 3 \times 5 \times 5

=34×52= 3^4 \times 5^2

34×52\boxed{3^4 \times 5^2}

Answer

(i) The total number of tiny squares in the picture is 2025. (ii) The prime factorization of the number of tiny squares is 34×523^4 \times 5^2.

More questions in FIO

Q1

Which of the following numbers are not perfect squares?

(i) 2032 (ii) 2048 (iii) 1027 (iv) 1089

Q2

Which one among 64264^2, 1082108^2, 2922292^2, 36236^2 has last digit 4?

Q3

Given 1252=15625125^2 = 15625, what is the value of 1262126^2?

(i) 15625 + 126

(ii) 15625+26215625 + 26^2

(iii) 15625 + 253

(iv) 15625 + 251

(v) 15625+51215625 + 51^2

Q4

Find the length of the side of a square whose area is 441 m2441\text{ m}^2.

Q5

Find the smallest square number that is divisible by each of the following numbers: 4, 9, and 10.

Q6

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.

Q7

How many numbers lie between the squares of the following numbers?

(i) 16 and 17 (ii) 99 and 100

Q8

In the following pattern, fill in the missing numbers:

12+22+22=321^2 + 2^2 + 2^2 = 3^2 22+32+62=722^2 + 3^2 + 6^2 = 7^2 32+42+122=1323^2 + 4^2 + 12^2 = 13^2

(a) 42+52+202=()24^2 + 5^2 + 20^2 = (\underline{\quad})^2

(b) 92+102+()2=()29^2 + 10^2 + (\underline{\quad})^2 = (\underline{\quad})^2

Q9

How many tiny squares are there in the following picture? Write the prime factorisation of the number of tiny squares.

Q10

Find the cube roots of 27000 and 10648.

Q11

What number will you multiply by 1323 to make it a cube number?

Q12

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.

Q13

You are told that 1331 is a perfect cube. Can you guess without factorisation what its cube root is? Similarly, guess the cube roots of 4913, 12167, and 32768.

Q14

Which of the following is the greatest? Explain your reasoning.

(i) 67366367^3 - 66^3

(ii) 43342343^3 - 42^3

(iii) 67266267^2 - 66^2

(iv) 43242243^2 - 42^2

← Back to Rational Numbers