Samacheer Kalvi Class 5 Maths Solutions Term 3 Chapter 2 Numbers InText Questions

Try This (Text Book Page.No 15)

Question. Write down the estimated value of numbers and find their sum. Also, find the difference of their sum.
Answer: To solve this, we first estimate each number to the nearest ten and then find the estimated sum. Next, we find the actual sum of the original numbers. Finally, we subtract the actual sum from the estimated sum to find the difference. This helps us understand how much the estimated sum varies from the true sum.

🎯 Exam Tip: Remember to clearly show both the estimated and actual sums before calculating the final difference to earn full marks.

Try This (Text Book Page.No 16)

Question. Write down the estimated value of numbers and divide. Then find the difference between estimated value and actual value.
Answer: We estimate the numbers to the nearest ten to make division simpler. Then we perform the estimated division. After that, we calculate the actual division of the original numbers. Finally, we find the difference between the estimated quotient and the actual quotient to see how close our estimation was. This practice helps improve quick mental math skills.

🎯 Exam Tip: When estimating for division, try to choose numbers that divide easily, even if it means rounding to a multiple of 10 or 5 rather than just the nearest 10.

Activity (Text Book Page.No 18)

Question. A. Color the number's row with the help of the following tips.
1. Orange colour to the prime number row.
2. Don't colour to the odd number row.
3. Blue colour to 6 in multiples row.
4. Orange colour to the square number row.
5. Dont colour to the even number row.
6. Blue colour to 8 in multiples row.
Answer: This activity involves identifying numbers based on specific properties (prime, odd, even, multiples, square numbers) and then 'coloring' their rows as instructed. The table below shows the numbers for this activity. In the actual exercise, you would use orange for rows with prime numbers and square numbers, and blue for rows with multiples of 6 and 8. Rows with odd or even numbers were to remain uncolored based on the rules.

🎯 Exam Tip: When working with number properties, clearly list the properties of each number (e.g., prime, composite, square, multiple) before applying any coloring or grouping rules.

B. Let us fill the number wheel

Question 1.
Answer: This number wheel requires filling in the missing numbers based on a pattern. Observing the existing numbers, we can see that the numbers opposite each other multiply to 21. For example, 3 x 7 = 21. Following this pattern, we can fill in the missing values. This exercise helps to practice multiplication and pattern recognition.
In simple words: The numbers opposite each other on the wheel multiply to 28. So, to find the missing number, divide 28 by the number on the opposite side.

🎯 Exam Tip: Look for simple arithmetic patterns like addition, subtraction, multiplication, or division between numbers, especially those directly opposite or adjacent in a wheel.

Question 2.
Answer: For this number wheel, we need to find the missing numbers by following a specific pattern. Here, the numbers on opposite sides of the wheel multiply to a consistent value of 4. For instance, 1 x 4 = 4. By applying this rule, we can determine the remaining numbers. This pattern identification strengthens multiplication skills.
In simple words: The numbers opposite each other on this wheel multiply to 28. Use this rule to find the missing numbers by dividing 28 by the number across from the blank.

🎯 Exam Tip: In number wheels, if multiplication doesn't work, check for addition, subtraction, or even sequential patterns around the wheel, or patterns related to the central number if one is present.

Question 3.
Answer: To complete this number wheel, we need to find the pattern linking the numbers. In this wheel, the numbers placed opposite each other sum up to 64. For example, 48 + 16 = 64. By using this addition rule, we can easily find the missing numbers. This pattern-finding activity helps in developing logical reasoning skills.
In simple words: The numbers directly across from each other on the wheel always add up to 64. Use this rule to fill in the empty spots.

🎯 Exam Tip: When missing multiple numbers, first find the pattern by comparing the numbers that are already complete in a pair (e.g., opposite each other), then apply that rule consistently.

Question. C. Complete the circle using the given four basic operators to get the number 20.
Answer: To complete this circle, we need to use the basic math operators (+, -, x, ÷) to make each expression equal to 20. By filling in the correct operators and numbers, we can solve each segment. This helps practice basic arithmetic and problem-solving skills.

The filled circle is:
In simple words: Each section connected to the center "20" must result in 20 when you do the math. Fill in the missing numbers using addition, subtraction, multiplication, or division to reach 20.

🎯 Exam Tip: For problems involving multiple operations to reach a target number, start with the operations given and deduce the missing numbers. Always double-check your calculations.

D. Fill in the blanks

Question 1. 5, 10, 15, ___, 25
Answer: The numbers in this sequence are increasing by 5 each time. This is an arithmetic progression where 5 is added to the previous number to get the next one. This simple addition pattern helps predict future numbers in the series.
20
In simple words: The numbers go up by 5 each time. So, after 15, the next number is 20.

🎯 Exam Tip: For number sequences, first look for constant differences (addition/subtraction) or constant multipliers (multiplication/division) between terms.

Question 2. 30, 24, ___, 126
Answer: This sequence appears to involve multiplication and addition. Let's analyze the pattern: \( 3 \times 10 = 30 \), \( 3 \times 8 = 24 \), \( 3 \times 6 = 18 \), \( 3 \times 42 = 126 \). This pattern isn't a simple arithmetic or geometric progression. Let's reconsider the numbers. If we assume the sequence is \( 30, 24, (X), (Y), 126 \), and the difference is decreasing by 6 each time, this gives \( 30 - 6 = 24 \), then \( 24 - 6 = 18 \). The missing number is 18.
18
In simple words: To get the next number, you subtract 6 from the one before it. So, 24 minus 6 is 18.

🎯 Exam Tip: When a simple pattern isn't obvious, check for a pattern in the differences between consecutive terms; sometimes the difference itself follows a pattern.

Question 3. 7, 9, 11, ____. 17
Answer: This sequence shows odd numbers increasing by 2 each time. It is an arithmetic progression with a common difference of 2. After 11, adding 2 gives 13, and then adding 2 again gives 15. Then 15 + 2 = 17, which matches the next number provided. Understanding such basic arithmetic sequences is key to many math problems.
13, 15
In simple words: The numbers go up by 2 each time. So, after 11 comes 13, and then 15.

🎯 Exam Tip: Always verify your identified pattern across all given numbers in the sequence, not just the first few, to avoid incorrect assumptions.

Question 4. 1, 4, 9, -, 25
Answer: This sequence represents perfect squares: \( 1^2=1 \), \( 2^2=4 \), \( 3^2=9 \). The next number in the pattern would be \( 4^2 \). Recognizing square numbers is a fundamental skill in number patterns. They are often found in geometric arrangements or simple growth series.
16
In simple words: These are square numbers (1x1, 2x2, 3x3). So the missing number is 4 times 4, which is 16.

🎯 Exam Tip: When numbers increase rapidly, consider patterns involving squares, cubes, or exponents rather than just simple addition or multiplication.

Question 5. 1, 4, 7, —-,13, --, 19
Answer: This sequence is an arithmetic progression where each number is obtained by adding 3 to the previous one. Starting from 1, we add 3 to get 4, then add 3 to get 7. So, \( 7+3=10 \), and \( 13+3=16 \). The pattern of adding a constant value is very common. The two missing numbers are 10 and 16.
10, 16
In simple words: Each number is 3 more than the one before it. So, after 7 comes 10, and after 13 comes 16.

🎯 Exam Tip: For sequences with two missing numbers, find the constant difference or ratio from the known numbers and apply it multiple times to fill the gaps.

E. Answer the following

Question 1. If BOOK is 43, Then PEN is ____.
Answer: In this code, each letter is assigned a numerical value based on its position in the alphabet (A=1, B=2, C=3, and so on). The value for "BOOK" is calculated as B(2) + O(15) + O(15) + K(11) = 2 + 15 + 15 + 11 = 43. Following this pattern for "PEN", we get P(16) + E(5) + N(14). This type of puzzle tests knowledge of alphabetical order and basic addition.
PEN = 16 + 5 + 14 = 35
In simple words: Each letter is turned into its number in the alphabet (A=1, B=2, etc.). Then, add up all the numbers for the word.

🎯 Exam Tip: For letter-to-number codes, always assume A=1, B=2 unless another system (like reverse alphabet or a shifted code) is clearly indicated by the example.

Question 2. If SCHOOL is 1938151512, Then CLASS is ____
Answer: In this coding system, each letter of the word is simply replaced by its corresponding position number in the alphabet. For "SCHOOL", S is 19, C is 3, H is 8, O is 15, O is 15, and L is 12, forming 1938151512. Applying this same direct substitution rule to "CLASS" will give us its code. This method is a straightforward letter-to-number cipher.
31211919
In simple words: Just write the position number of each letter in the alphabet next to each other to make the code.

🎯 Exam Tip: When a coded number is very long, it often means each letter is directly replaced by its two-digit (or one-digit) alphabetical position without any addition or complex calculation.

Question 3. If BAG is 10, Then BOOK is ____
Answer: This coding system assigns a numerical value to each letter based on its alphabetical position (A=1, B=2, C=3, etc.) and then sums these values. For "BAG", B(2) + A(1) + G(7) = 2 + 1 + 7 = 10. We apply the same logic to "BOOK". This type of question checks a student's familiarity with alphabet sequencing and basic addition skills. The answer is found by adding up the numerical values for B, O, O, and K.
2 + 15 + 15 + 11 = 43
In simple words: The numbers for each letter in the alphabet are added together to get the word's code.

🎯 Exam Tip: When the example word's code is a sum, ensure you correctly identify the value of each letter from its alphabetical position before adding.

Question 4. If LION is 50. Then TIGER is ____
Answer: This problem uses a coding system where the alphabetical position of each letter is assigned a numerical value (A=1, B=2, ...). The value for "LION" is calculated by summing the letter values: L(12) + I(9) + O(15) + N(14) = 12 + 9 + 15 + 14 = 50. To find the value for "TIGER", we apply the same method. This type of coding helps improve quick recall of letter positions and mental arithmetic.
20 + 9 + 7 + 5 + 18 = 59
In simple words: Each letter is changed to its number in the alphabet. Then, all these numbers for the word are added up.

🎯 Exam Tip: Practice quickly reciting the alphabet with corresponding numbers to improve speed and accuracy on these types of coding questions.

Question 5. If HEN is 8514, Then COCK is ____
Answer: In this coding method, each letter's alphabetical position is directly written out as its code, concatenated together without any mathematical operations. For "HEN", H is 8, E is 5, N is 14, so it becomes 8514. To find "COCK", we simply substitute the position of each letter in the alphabet. This is a common form of letter-to-number cipher. This exercise helps in remembering the alphabetical order of letters.
315311
In simple words: Write down the alphabet number for each letter, one after another, to get the code for the word.

🎯 Exam Tip: Be careful with two-digit letter positions (like 10-26); ensure they are treated as individual letter codes rather than being split or merged incorrectly.