Page 71 - ICSE Math 8

Example 10: There are 10 hidden mines in the grid shown alongside. 2 0 1
The numbers in various squares indicate the total number 3 1 2
of mines hidden in 8 squares around the numbered square. 1 0 1
The numbered squares do not have any mines. Can you 2 1 0
detect the 10 mines? 1 0 1
Solution: M 2 M × 0 × 1 × 1 1 1 1

× 3 × 1 × 2 M × 1 1 1 2 2
M 1 0 × 1 M × × 1 1
× 2 × × × × 1 0 M —mines
M 1 × × 0 × 1 ×
1 1 × 1 × × 1 M
× 1 × M 1 1 2 2
M × 1 × 1 × M ×

EXERCISE 5.3
1. Solve the following.

(a) X Y (b) 1 B (c) 2 P Q (d) R S 7
+ 3 7 × B + P Q 1 + 7 R S

9 X 9 B Q 1 8 9 8 R

2. Think of a number. Double it. Add 18. Take away 10. Halve it. Take away 4. Now what do you get and
why?

3. Place the digits 1 to 9 in the circles so that the sum of three
numbers on each diameter equals 15.

4. Fill in the circles with the correct digits. 6 3 4

×

4
8
×
0

5. Fill in the blank squares with 2-digit prime numbers so that the 41
sum of the numbers in both the horizontal and vertical squares is
161.
13 17

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