Samacheer Kalvi Class 5 Maths Solutions Term 1 Chapter 2 Numbers Exercise 2.7

Question 1. Multiply
a. 473 x 48
b. 4052 x 19
c. 876 x 25
d. 854 × 21
e. 417 x 39
f. 870 x 28
Answer:
a. To find the product of 473 and 48, we multiply 473 by 8 to get 3784. Then, we multiply 473 by 40 (which is 473 multiplied by 4, shifted one place left), resulting in 18920. Adding these two partial products, 3784 and 18920, gives the final total of 22,704. This method breaks down multiplication into simpler parts.
\( \begin{array}{r} 473 \\ \times \quad 48 \\ \hline 3784 \\ + \quad 18920 \\ \hline 22,704 \end{array} \)
b. To multiply 4052 by 19, first multiply 4052 by 9 to get 36468. Next, multiply 4052 by 10 (which is 40520). Add these two results together: \( 36468 + 40520 \), which gives the product of 76,988. This is a common method for multiplying numbers with two digits.
\( \begin{array}{r} 4052 \\ \times \quad 19 \\ \hline 36468 \\ + \quad 40520 \\ \hline 76,988 \end{array} \)
c. When multiplying 876 by 25, we start by multiplying 876 by 5 to get 4380. Then, we multiply 876 by 20 (which is 876 multiplied by 2, shifted one place left), giving us 17520. Adding these two values, 4380 and 17520, results in the final product of 21,900. Breaking down the multiplication makes it easier to handle larger numbers.
\( \begin{array}{r} 876 \\ \times \quad 25 \\ \hline 4380 \\ + \quad 17520 \\ \hline 21,900 \end{array} \)
d. To multiply 854 by 21, first we multiply 854 by 1, which is 854. Then, we multiply 854 by 20 (854 multiplied by 2, shifted one place left), which gives 17080. Adding these two partial products, 854 and 17080, we get the answer of 17,934. Understanding place value is very important in multiplication.
\( \begin{array}{r} 854 \\ \times \quad 21 \\ \hline 854 \\ + \quad 17080 \\ \hline 17,934 \end{array} \)
e. To find 417 multiplied by 39, we first multiply 417 by 9, which results in 3753. Next, we multiply 417 by 30 (which is 417 multiplied by 3, shifted one place left), giving us 12510. Adding these two values, 3753 and 12510, gives the total product of 16,263. This method ensures all parts of the numbers are correctly multiplied.
\( \begin{array}{r} 417 \\ \times \quad 39 \\ \hline 3753 \\ + \quad 12510 \\ \hline 16,263 \end{array} \)
f. To multiply 870 by 28, we first multiply 870 by 8, which gives 6960. Then, we multiply 870 by 20 (870 multiplied by 2, shifted one place left), which results in 17400. Adding the two partial products, 6960 and 17400, yields the final answer of 24,360. Using this expanded form of multiplication helps to prevent errors.
\( \begin{array}{r} 870 \\ \times \quad 28 \\ \hline 6960 \\ + \quad 17400 \\ \hline 24,360 \end{array} \)
In simple words: To multiply numbers, you break it down into smaller multiplication steps for each digit and then add the results, remembering to shift values for each place.

🎯 Exam Tip: Always double-check your addition steps in multiplication, as a small error can change the entire final product. Using graph paper can help keep numbers aligned.

Question 2. Answer the following:
a. There are 55 mangoes in a basket, Cost of one mango is Rs. 15. What is the total cost of 55 mangoes?
b. There are 55 passengers in a bus. Each of them get tickets of Rs. 25. What is the amount collected by the conductor?
c. A classroom has 23 benches, cost of one bench is Rs. 725. What is the total cost of all the 23 benches?
d. There are 675 people living in a village. One person uses 25 l of water daily. How much of water is needed for the village for one day?
e. In a building, there are 26 rooms, cost of painting for one room is Rs. 950. What is the total cost of painting the building?
Answer:
a. Total number of mangoes = 55
Cost of one mango = Rs. 15
Total cost of 55 mangoes = \( 55 \times 15 = 825 \)
So, the total cost is Rs. 825. This shows how to calculate the total cost for multiple items.
\( \begin{array}{r} 55 \\ \times \quad 15 \\ \hline 275 \\ + \quad 550 \\ \hline 825 \end{array} \)
b. Total number of Passengers = 55
Amount collected for each one = Rs. 25
Total amount collected by the conductor = \( 55 \times 25 = 1375 \)
Therefore, the conductor collected Rs. 1,375 in total. This is a common way to find the total earnings from selling many items at the same price.
\( \begin{array}{r} 55 \\ \times \quad 25 \\ \hline 275 \\ + \quad 1100 \\ \hline 1375 \end{array} \)
c. Total number of benches = 23
Cost of one bench = Rs. 725
Cost of 23 benches = \( 725 \times 23 = 16675 \)
So, the total cost for all 23 benches is Rs. 16,675. This helps in budgeting for classroom supplies.
\( \begin{array}{r} 725 \\ \times \quad 23 \\ \hline 2175 \\ + \quad 14500 \\ \hline 16675 \end{array} \)
d. Total number of people in a village = 675
Water used by them daily = 25 litres
Need of water for the village per day = \( 675 \times 25 = 16875 \) litres
Thus, the village needs 16,875 litres of water every day. This kind of calculation is important for managing community resources.
\( \begin{array}{r} 675 \\ \times \quad 25 \\ \hline 3375 \\ + \quad 13500 \\ \hline 16875 \end{array} \)
e. Total number of rooms = 26
Cost of painting for one room = Rs. 950
Cost of painting for 26 rooms = \( 950 \times 26 = 24700 \)
So, the total cost to paint the entire building is Rs. 24,700. This helps estimate expenses for building maintenance and renovation.
\( \begin{array}{r} 950 \\ \times \quad 26 \\ \hline 5700 \\ + \quad 19000 \\ \hline 24700 \end{array} \)
In simple words: For word problems asking for a total, you multiply the number of items by the cost or quantity per item.

🎯 Exam Tip: Always read word problems carefully to identify the numbers given and what you need to find. Make sure to use the correct operation (multiplication for 'total cost' or 'total quantity').