Math Reasoning Exercise: Set 5 - Questions 1 to 3
Question 1
Solution 1:
-7+19
22 +(-13)
Solution 2:
18+(-6)
(-3)+(12)
Solution 3:
12+0
3+6
Solution 4:
6+6
9+0
Solution 5:
11+1
4+5
Solution 6:
7+5
8+1
There are more solutions. Did you find the others..?
Question 2
Now lets try sum 2.. This is a fun sum.
Looking at the sum, we can identify that
A+D gives lowest sum. So A,D has to be small numbers.
C+F gives the highest sum,
And D+E+F = 15.
So F has to be a big number. Lets assume its 9.
C+F =16 C = 7
Now D+E + 9 = 15. So D+ E =6
E has to be a small number.
A+D =4 so A can be 1and D can be 3 or A can be 3 and D can be 1. They cant be 2+2 as each number should be unique.
If I put D as 3 then E has to be 3. That’s not possible as each number should be unique.
So put D as 1
Now you can solve the grid.
Row 1- 3 4 7
Row 2 -1 5 9
So the trick is. Search for biggest possible sum and smallest possible sum.
Now try a harder sum. Answers are below
Question 3
Solution:
Put brackets
Remember digits are from 1 to 9. Each digit is used only once
_ + (13 × _ ÷ _ ) + _ + (12 × _ ) – _ – 11 + ( _ × _ ÷ _ ) – 10=66
Fill in some numbers to guess and check
Try using numbers 1 to 9, from left to right?
1 + (13 × 2 ÷ 3) + 4 + (12 × 5) – 6 – 11 + (7 × 8 ÷ 9) – 10 = 52.88…
write the numbers in descending order, from 9 to 1
9 + (13 × 8 ÷ 7) + 6 + (12 × 5) – 4 – 11 + (3 × 2 ÷ 1) – 10 = 70.85…
Use trial and error move the numbers around until till you get 66.
answer
9 + (13 × 4 ÷ 8) + 5 + (12 × 6) – 7 – 11 + (1 × 3 ÷ 2) – 10 = 66