{"id":61959,"date":"2026-05-08T18:22:26","date_gmt":"2026-05-08T10:22:26","guid":{"rendered":"https:\/\/blog-admin.thethinkacademy.com\/?p=61959"},"modified":"2026-05-08T18:22:28","modified_gmt":"2026-05-08T10:22:28","slug":"fractions-decimals-gauss","status":"publish","type":"post","link":"https:\/\/blog-admin.thethinkacademy.com\/blog\/2026\/05\/08\/fractions-decimals-gauss\/","title":{"rendered":"Percentage of 11 out of 15: How to Convert Scores to Percentages (Gauss Contest Guide)"},"content":{"rendered":"\n

Converting a score like 11 out of 15 to a percentage is one of the most practical mathematics skills a student can have \u2014 and it is also directly tested on the Gauss math contest<\/a> in problems involving percentages, fractions, and decimals. This guide explains exactly how to find the percentage of 11 out of 15, works through other commonly searched score conversions including 36 out of 40, 25 out of 30, 35 out of 40, 43 out of 50, and 18 out of 25, and then builds from these foundations to the more complex percentage problems that appear in Gauss past papers. Whether your child needs to convert a test score, solve a percentage word problem, or answer a Gauss contest question involving percentages, decimals and fractions, this guide covers all of it with full worked examples.<\/p>\n\n\n\n

Signing up for the Gauss contest or thinking about registering? Check out: Gauss Contest: What Canadian Students Need to Know Before They Compete<\/a>.<\/p>\n\n\n\n

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\"score<\/a><\/figure>\n<\/div>\n\n\n
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What is a percentage and how does it work?<\/strong><\/h2>\n\n\n\n

A percentage is a way of expressing a number as a fraction of 100. The word percent comes from the Latin per centum meaning out of one hundred. When you say 75%, you mean 75 out of every 100 \u2014 or equivalently, the fraction 75\/100.<\/p>\n\n\n\n

The core idea behind every percentage calculation is the same: you are scaling a fraction so the denominator becomes 100.<\/p>\n\n\n\n

The percentage formula:<\/strong><\/p>\n\n\n\n

Percentage = (part \/ whole) x 100<\/strong><\/p>\n\n\n\n

This formula works for every score conversion, every percentage word problem, and every percentage question on the Gauss math contest. Memorise it and apply it consistently.<\/p>\n\n\n\n

The relationship between percentages, decimals and fractions<\/strong><\/h3>\n\n\n\n

Percentages, decimals and fractions are three ways of expressing the same value. Converting fluently between all three is one of the core skills tested on the Gauss contest.<\/p>\n\n\n\n

Fraction<\/th>Decimal<\/th>Percentage<\/th><\/tr><\/thead>
1\/2<\/td>0.5<\/td>50%<\/td><\/tr>
1\/4<\/td>0.25<\/td>25%<\/td><\/tr>
3\/4<\/td>0.75<\/td>75%<\/td><\/tr>
1\/5<\/td>0.2<\/td>20%<\/td><\/tr>
2\/5<\/td>0.4<\/td>40%<\/td><\/tr>
1\/10<\/td>0.1<\/td>10%<\/td><\/tr>
3\/10<\/td>0.3<\/td>30%<\/td><\/tr>
1\/8<\/td>0.125<\/td>12.5%<\/td><\/tr>
1\/3<\/td>0.333…<\/td>33.3…%<\/td><\/tr>
2\/3<\/td>0.666…<\/td>66.6…%<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Converting fraction to percentage:<\/strong> multiply by 100. Converting percentage to fraction:<\/strong> divide by 100 and simplify. Converting decimal to percentage:<\/strong> multiply by 100. Converting percentage to decimal:<\/strong> divide by 100.<\/p>\n\n\n\n

For a full set of practice problems converting between all three forms, our guide to equivalent fractions covers the proportional reasoning that underpins these conversions in depth \u2014 see Equivalent Fractions Worksheet: Practice Problems and Examples<\/a>.<\/p>\n\n\n\n

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Percentage of 11 out of 15<\/strong><\/h2>\n\n\n\n

Finding the percentage of 11 out of 15 is a direct application of the percentage formula.<\/p>\n\n\n\n

Method:<\/strong><\/p>\n\n\n\n

Percentage = (part \/ whole) x 100 = (11 \/ 15) x 100 = 0.7333… x 100 = 73.33…%<\/p>\n\n\n\n

Rounded to the nearest whole number: 73%<\/strong> Rounded to one decimal place: 73.3%<\/strong><\/p>\n\n\n\n

As a fraction:<\/strong> 11\/15 cannot be simplified further since 11 is prime and does not divide 15.<\/p>\n\n\n\n

As a decimal:<\/strong> 11 \u00f7 15 = 0.7333… (the 3 repeats indefinitely)<\/p>\n\n\n\n

Why 11 out of 15 does not give a clean percentage<\/strong><\/h3>\n\n\n\n

Unlike fractions whose denominators are factors of 100 (such as 4, 5, 10, 20, 25, 50), the fraction 11\/15 does not convert to a terminating decimal. This is because 15 = 3 x 5, and 3 is not a factor of 100. Whenever the denominator of a simplified fraction contains a prime factor other than 2 or 5, the decimal expansion will repeat rather than terminate.<\/p>\n\n\n\n

For the Gauss math contest<\/a>, you need to be comfortable working with both terminating and repeating decimals. Recognising that 1\/3 = 0.333…, 2\/3 = 0.666…, 1\/6 = 0.1666…, and 1\/15 = 0.0666… will help you work with fractions that have 3 in the denominator more efficiently.<\/p>\n\n\n\n

Quick percentage reference \u2014 what is 11 out of 15?<\/strong><\/h3>\n\n\n\n
Score<\/th>Fraction<\/th>Decimal<\/th>Percentage<\/th><\/tr><\/thead>
11 out of 15<\/td>11\/15<\/td>0.7333…<\/td>73.3%<\/td><\/tr>
12 out of 15<\/td>4\/5<\/td>0.8<\/td>80%<\/td><\/tr>
13 out of 15<\/td>13\/15<\/td>0.8666…<\/td>86.7%<\/td><\/tr>
14 out of 15<\/td>14\/15<\/td>0.9333…<\/td>93.3%<\/td><\/tr>
15 out of 15<\/td>1<\/td>1.0<\/td>100%<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
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36 out of 40 as a percentage<\/strong><\/h2>\n\n\n\n

36 out of 40 is a cleaner calculation than 11 out of 15 because 40 is a factor-of-100-friendly number.<\/p>\n\n\n\n

Method 1 \u2014 formula:<\/strong> Percentage = (36 \/ 40) x 100 = 0.9 x 100 = 90%<\/strong><\/p>\n\n\n\n

Method 2 \u2014 scaling the fraction:<\/strong> 36\/40 = 9\/10 (divide both by 4). 9\/10 = 90\/100 = 90%<\/strong><\/p>\n\n\n\n

Method 3 \u2014 recognising the fraction:<\/strong> 36\/40 simplifies to 9\/10, which is a benchmark fraction. 9\/10 = 90% is worth knowing directly.<\/p>\n\n\n\n

Answer: 36 out of 40 = 90%<\/strong><\/p>\n\n\n\n

H3: 35 out of 40 as a percentage<\/strong><\/p>\n\n\n\n

Method:<\/strong> 35\/40 = 7\/8 (divide both by 5). 7\/8 as a percentage: (7\/8) x 100 = 700\/8 = 87.5%<\/p>\n\n\n\n

Answer: 35 out of 40 = 87.5%<\/strong><\/p>\n\n\n\n

Alternatively: 35\/40 = 0.875. Multiply by 100 to get 87.5%.<\/p>\n\n\n\n

Score comparison table out of 40<\/strong><\/h3>\n\n\n\n
Score<\/th>Simplified fraction<\/th>Percentage<\/th><\/tr><\/thead>
32\/40<\/td>4\/5<\/td>80%<\/td><\/tr>
33\/40<\/td>33\/40<\/td>82.5%<\/td><\/tr>
34\/40<\/td>17\/20<\/td>85%<\/td><\/tr>
35\/40<\/td>7\/8<\/td>87.5%<\/td><\/tr>
36\/40<\/td>9\/10<\/td>90%<\/td><\/tr>
37\/40<\/td>37\/40<\/td>92.5%<\/td><\/tr>
38\/40<\/td>19\/20<\/td>95%<\/td><\/tr>
39\/40<\/td>39\/40<\/td>97.5%<\/td><\/tr>
40\/40<\/td>1<\/td>100%<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
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43 out of 50 as a percentage<\/strong><\/h2>\n\n\n\n

50 is one of the most convenient denominators for percentage conversion because 50 x 2 = 100.<\/p>\n\n\n\n

Method:<\/strong> 43\/50 x 2\/2 = 86\/100 = 86%<\/strong><\/p>\n\n\n\n

Multiplying both numerator and denominator by 2 scales the fraction directly to hundredths \u2014 no division needed.<\/p>\n\n\n\n

Answer: 43 out of 50 = 86%<\/strong><\/p>\n\n\n\n

Why 50 is easy to convert<\/strong><\/h3>\n\n\n\n

Any fraction with denominator 50 converts to a percentage instantly by doubling the numerator. This is because 100\/50 = 2, so multiplying numerator and denominator by 2 always gives a denominator of 100.<\/p>\n\n\n\n