# 10 most difficult numbers riddles

A list of ten (out of 39) numbers related questions that are the most often answered incorrectly

Numbers quiz
## What is the diameter of the Milky Way?

100 000 thousand light years. The diameter of our galaxy - the Milky Way is 100,000 light years. The Sun is located about 26,000 light years from its center.

very hard

19%

100 000 thousand light years

100 000 thousand light years

19%

200 000 thousand light years

200 000 thousand light years

26%

500 000 thousand light years

500 000 thousand light years

32%

1 000 000 thousand light years

1 000 000 thousand light years

21%

Created by: Tschuka .
Statistics based on 425 answers in 2 languages
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## What number is the pattern for the construction of Dante Alighieri's song "Divine Comedy"?

3. The Divine Comedy is composed of 14,233 lines that are divided into three canticas – Inferno (Hell), Purgatorio (Purgatory), and Paradiso (Paradise) – each consisting of 33 cantos . The number "three" is prominent in the work, represented in part by the number of canticas and their lengths. Additionally, the verse scheme used, terza rima, is hendecasyllabic with the lines composing tercets according to the rhyme scheme aba, bcb, cdc, ded,

very hard

23%

9

9

29%

3

3

23%

7

7

41%

5

5

5%

Created by: Tschuka .
Statistics based on 1901 answers in 2 languages
»

## Which of the following is true for the solution with the pH=0?

The OH − ion concentration is smaller than the H+ ion concentration. In chemistry, pH is a numeric scale used to specify the acidity or alkalinity of an aqueous solution. It is the negative of the logarithm to base 10 of the activity of the hydrogen ion .Traditionally the pH is being defined as: pH = - log10 [H+], where [H+] it is a H+ ions concentration in mol/dm^3 (M). So if pH = 0 this H+ ions concentration is 1 mol/dm^3 and the solution is strongly acidic.

very hard

25%

the OH − ion concentration is smaller than the H+ ion concentration

the OH − ion concentration is smaller than the H+ ion concentration

25%

the OH − ion concentration is greater than the H+ ion concentration

the OH − ion concentration is greater than the H+ ion concentration

19%

the OH − ion concentration is equal of the H+ ion concentration

the OH − ion concentration is equal of the H+ ion concentration

28%

Such solution doesn't exist

Such solution doesn't exist

26%

Created by: Paweł Kołodziejczyk.
Statistics based on 3381 answers in 2 languages
»

## Which of the following Roman numerals stands for 4?

Both IV and IIII. Both notations are correct and historically Roman numerals were often written less consistently than today. The notation 'IIII' is often seen on clock faces. The reason for that may be practical, to avoid confusing the IV and VI when the clock is held upside down (although other theories also exist).

very hard

26%

IV

IV

71%

IIII

IIII

1%

Both IV and IIII

Both IV and IIII

26%

None of the above

None of the above

1%

Created by: globalquiz.org.
Statistics based on 6363 answers in 4 languages
»

## In what period of time does the Sun make a full turn around the center of the Milky Way?

Within every 225 million years. The sun performs a full turn around the center of our galaxy during 225 million years.

very hard

26%

within every 225 million years

within every 225 million years

26%

within 250 million years

within 250 million years

32%

within 300 million years

within 300 million years

23%

within 350 million years

within 350 million years

17%

Created by: Tschuka .
Statistics based on 715 answers in 2 languages
»

## A given natural number is divisible by 4 if and only if ...?

The number created from the last two digits is divisible by 4. The last two digits form a number that is divisible by 4; 40,832: 32 is divisible by 4. If the tens digit is even, the ones digit must be 0, 4, or 8. If the tens digit is odd, the ones digit must be 2 or 6. 40,832: 3 is odd, and the last digit is 2. Twice the tens digit, plus the ones digit is divisible by 4.

very hard

27%

the last digit is divisible by 4

the last digit is divisible by 4

15%

the last two digits are divisible by 4

the last two digits are divisible by 4

32%

the sum of the last two digits is divisible by 4

the sum of the last two digits is divisible by 4

23%

the number created from the last two digits is divisible by 4

the number created from the last two digits is divisible by 4

27%

Created by: Tschuka .
Statistics based on 651 answers in 2 languages
»

## What number is considered unlucky in Italy?

17. In Italian culture, the number 17 is considered unlucky. When viewed as the Roman numeral, XVII, it is then changed anagrammatically to VIXI, which in the Latin language translates to "I lived", the perfect implying "My life is over."

very hard

28%

17

17

28%

13

13

17%

15

15

12%

7

7

41%

Created by: Ninjai.
Statistics based on 574 answers in 2 languages
»

## At what temperature does the water have the highest density?

4°C (39.2°F). Increasing the temperature generally decreases the density, but water is a notable exception: the density of water increases between its melting point at 0 °C and 4 °C. Similar behavior is observed in silicon at low temperatures.

very hard

29%

0°C (32°F)

0°C (32°F)

33%

100°C (212°F)

100°C (212°F)

16%

-273°C (-459.4°F)

-273°C (-459.4°F)

20%

4°C (39.2°F)

4°C (39.2°F)

29%

Created by: Tschuka .
Statistics based on 4478 answers in 2 languages
»

## What is the largest integer ever used in a mathematical proof?

Graham's number is an enormous number that arises as an upper bound on the answer of a problem in the mathematical field of Ramsey theory. The number was published in the 1980 Guinness Book of World Records, adding to its popular interest.

very hard

31%

Googolplex

Googolplex

13%

Googol

Googol

38%

Graham's number

Graham's number

31%

Centillion

Centillion

17%

Created by: Ninjai.
Statistics based on 3756 answers in 2 languages
»

## Which numeral system was in use in ancient Sumer and Babylon?

Sexagesimal. Remnants of highly composite sexagesimal system are in use even today for measuring angles, geographic coordinates and especially time. An hour of time is divided into 60 minutes, which in turn are divided into 60 seconds.

very hard

32%

octal

octal

22%

binary

binary

20%

decimal

decimal

24%

sexagesimal

sexagesimal

32%

Created by: smyru.
Statistics based on 13710 answers in 2 languages
»

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