This is viral math brainteaser from Japan.

### It is Easy But Tricky

9 – 3 ÷ 1/3 + 1 = ?

#### Most people will find answer as 9 but the Correct Answer is 1

Explanation:

The most common mistake is writing the 1/3 as: 9 – 3 ÷ 1/3 + 1

Most calculators will not group the 1/3, so the calculator evaluates: 9 – 3/1/3 + 1

= 9 – 3/3 + 1

= 9 – 1 + 1

= 9

The correct answer is found by grouping 1/3 with parentheses and following the order of operations, with division taking precedence.

9 – 3 ÷ (1/3) + 1

= 9 – 9 + 1

= 0 + 1

= 1

Source (English)

http://en.rocketnews24.com/2015/12/05/does-this-math-problem-prove-that-japans-20-somethings-are-getting-dumber/

Sources (Japanese)

http://www.j-cast.com/2015/12/03252296.html?p=all

http://www.yukawanet.com/archives/4618548.html

## 4 replies on “Viral Math Problem – Try It”

You answer is still wrong the order of operation has addition BEFORE subtraction so the answer is -1 .. 9 – 9 + 1 …. 9 -10 = -1 … you should always follow the order of operations PEDMAS (BEDMAS)

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Personally think my answer is better and clearer:

Most people will find answer as 9 but the Correct Answer is 1

Explanation:

The most common mistake is writing the 1/3 as: 9 – 3 ÷ 1/3 + 1

rather than treating it as 1/3 (one third – a fraction)

Most calculators will not group the 1/3, so the calculator evaluates: 9 – 3 ÷ 1 ÷ 3 + 1

= 9 – 3/3 + 1

= 9 – 1 + 1

= 9

But if you remember back to school you would do this equation as:

3 1

9 – ( – ÷ – ) + 1

1 3

3 3

= 9 – ( – x – ) + 1

1 1

Remember that when you change a division to a multiply you turn the

fraction upside down. You can no just multiply the numerators and denominators to give:

9

= 9 – ( – ) + 1

1

= 9 – 9 + 1

= 1

Note you will also get the correct result if you followed my hint and used 0.33333333 instead of 1/3

in this case you get

9 – 3 ÷ 0.3333333333 + 1

= 9 – 9 + 1

= 9

(note you need to round it as the 1/3 in decimal is actually 0.333 repeator)

Thank you for your explanation. I will try to edit post to simplify explanation.