class 8 NCERT bridge course Answers Activity 1W1.3: Recreational Puzzles

 Activity W1.3: Recreational Puzzles 

Students may be asked to play this game either individually or in pairs. 

They may be motivated to disclose their strategy before the class. 

Fill in the missing numbers

 1. The missing values are the whole numbers between 1 and 9. 

2. Each number is used only once.

3. Each row is an arithmetic equation. 

4. Each column is an arithmetic equation. 

5. Remember that multiplication and division are performed before addition and subtraction

Solve the 2nd Column

The equation is:  4 − A +3=2    

-A = 2-7

A = 5

Automatically the 2nd Row solved 

2 x 5 + 8 = 18

Solve the 1st column

A + 2 + B = 15

Solve the 3rd column

C + 8 - D = 0

C - D = -8

The numbers C and D must differ by -8. Possible pairs (from 1-9 without repeats):

• $A=2,C=10$ (from 1-9 without repeats so not possible)

• So only possible answer is C=1,D=9

Solve the 1st Row

A - 4 - C = 1

A - C = 1 +4

A - C = 5

The numbers $\mathrm{A\; and\; C\; must\; differ\; by\; 5.\; Possible\; pairs\; (from\; 1-9\; without\; repeats):}$

• 

Solve the 3rd Row

B - 3 X D = -20

D = 9

B - 3 x 9 = - 20

B - 27 = -20

B = -20 + 27

B = 7

Solution for the puzzle