Puzzles Questions

In each triangle, multiply the lower two numbers together and add the upper number to give the value at the centre.

From the assumption and trial and error method,

last three digits sum must leave the same digit as the answer. It is possible only if the answer must be units digit number leaving tens digit as carry.

And the possible 3rd digit is 5. Since 5 + 5 + 5 = 15 

Now, 2nd step is  1 + x + x + x = 5

=> 3x = 4

It is possible with x = 8. 8 + 8 + 8 + 1 = 25 leaving 2 as carry. 

Now, 3rd step is 2 + x + x + x = 5 => x = 1

Hence, the three dgits are 1, 8, 5.

185 + 185 + 185 = 555. 

YEAR - 1 E

WEEK - 2 E

DAY - 0 E

Hence, the letter 'E', comes once in a year, twice in a week and never in a day.

A Libraury. It has more number of story books in it to read.

The required number 100.

It is not an odd number and is not higher than 100 and greater than 90.

When we subtract 100 from 100, we get nothing i.e, 0.

A cup.

From the hints,

Only two options for 1st and 2nd digits => 4,2 and 9,3 since it is single digits

Sum of second and third digit  = 10 

If 2 => 3rd digit = 8

If 3 => 3rd digit = 7

4th digit = 2nd digit + 1 => (2+1 =3) or (3+1 = 4)

Sum of all digits = 30

Let 5th digit be x

=> 1st possibility = 4 + 2 + 8 + 3 + x = 30 => x = 13 (Not possible since it has 2 digits)

=> 2nd possibility = 9 + 3 + 7 + 4 + x = 30 => x = 7

Therefore, the PIN is 93747 

Given 

1 = 1 => 1 x 11 = 11

2 = 22 => 2 x 11 = 22

3 = 33 => 3 x 11 = 33

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Similarly,

11 => 11 x 11 = 121.