PREVIOUS |
NEXT |

**Q III) Solve the given problems**

**a)
Find the sum using
short cut method**

**1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13
+ 14 **

**Answer: 1 + 14 = 15**

**2 + 13 = 15**

**3 + 12 = 15**

**4 + 11 = 15**

**5 + 10 = 15**

**6 + 9 = 15**

**7 + 8 = 15**

**You stop at 7 because then after wards you are
repeating the number eg. 8 + 7, 9 + 6 etc**

**Now we have 15 repeating 7 times so we get**

**15 x 7 = 105**

**b) Draw the layout map of your classroom**

**Answer: This map can be drawn by reading the text book**

**c) Match each solid shape to its net**

**LET MJE EXPLAIN A LITTLE BIT OF CONVERTING SOLID SHAPE TO NET
DRAWING. IN THE FIGURE SHOWN ABOVE ON THE LEFT HAND SIDE WE HAVE
CUBOID, CYLINDER AND PYRAMID IN SOLID SHAPE. NOW WHEN WE CUT THESE SOLID
SHAPES AND UNFOLD IT ON PIECE OF PAPER THEN THE
DIAGRAM WE GET IS SHOWN ON RIGHT HAND SIDE OF THE FIGURE. SO THAT IS WHAT WE HAVE
DONE MATCHING SOLID SHAPE WITH NET DRAWING.**

**d) The cost of a movie ticket is Rs. 50.75. Find the cost of 5 such
movie tickets**

**Answer: Here you get answer by cross multiplication.**

**1 movie ticket ====== Rs. 50.75**

**5 tickets =========== ?**

**? x 1 = 5 x 50.75**

**? = 253.75 Rs. Therefore 5 ticket costs Rs. 253.75**

**e) Find the HCF of 70, 105 and 175**

**i) **

**2 | 70**

**5 | 35 **

** 7 | 7 **

** | 1**

**so you have: 2 x 5 x 7 **

**ii) 3 | 105**

** 5 | 35 **

** 7 | 7 **

** | 1 **

**so we have 3 x 5 x 7**

**iii) 5 | 175 **

** 5 | 35 **

** 7 | 7
**

** |
1 **

**so we have 5 x 5 x 7 **

**Hence Highest common factor is 5 x 7 = 35**

**The method shown above for finding HCF is easy for
children to grasp.**

**While calculating HCF or LCM you should have list of
prime numbers from 1 to 20, they are:**

**1,2,3,5,7,11,13, 17, and 19. These numbers can
calculate HCF or LCM for numbers from 1 to 400.**

**In exam I do not think that teachers would ask to
calculate HCF for numbers greater then 400. **

**For numbers from 1 to 100 you need to remember prime
numbers 1,2,3, 5 and 7.**