RBSE Solutions Class 5 Maths Chapter 17 Mental Mathematics Exercise 17.1

(i) Calculate: \( 523 + 59 \)
(a) 452
(b) 800
(c) 582
Answer: (c) 582
In simple words: To find the right answer, you need to add 523 and 59 together. When you add these numbers, the sum is 582, which matches option (c).

🎯 Exam Tip: Always double-check your addition by adding the numbers again or by using a reverse operation like subtraction, if time permits.

(ii) Calculate: \( 365 + 28 \)
(a) 792
(b) 393
(c) 462
Answer: (b) 393
In simple words: Add 365 and 28. The total you get is 393. This number is given as option (b), making it the correct choice.

🎯 Exam Tip: For mental math, try to break down numbers. For instance, 28 can be 20 + 8. Add 20 first, then 8, to make calculations quicker.

(iii) Calculate: \( 473 + 38 \)
(a) 511
(b) 6857
(c) 9803
Answer: (a) 511
In simple words: When you add 473 and 38, the sum is 511. This answer matches option (a).

🎯 Exam Tip: Pay attention to carrying over digits in addition problems. A small error can lead to a completely different result.

(iv) Calculate: \( 700 - 35 \)
(a) 601
(b) 121
(c) 665
Answer: (c) 665
In simple words: Subtract 35 from 700. The number left over is 665. Option (c) gives this exact number.

🎯 Exam Tip: When subtracting from a number with zeros, remember to borrow correctly from the left. It helps to think of 700 as 690 + 10.

(v) Calculate: \( 864 - 59 \)
(a) 805
(b) 4242
(c) 2671
Answer: (a) 805
In simple words: If you take away 59 from 864, the remaining number is 805. This means option (a) is the correct answer.

🎯 Exam Tip: For subtractions like these, sometimes it's easier to subtract a rounded number (like 60) and then add back the difference (add 1). So, 864 - 60 = 804, then 804 + 1 = 805.

(vi) Calculate: \( 652 - 48 \)
(a) 5592
(b) 604
(c) 2671
Answer: (b) 604
In simple words: When you subtract 48 from 652, you get 604. This value matches option (b).

🎯 Exam Tip: Always align the numbers correctly by their place values (ones, tens, hundreds) before performing addition or subtraction to avoid errors.