GCSE FDP equivalence Practice Questions

Free GCSE FDP equivalence practice questions with full step-by-step worked solutions. Covers fraction to decimal, common conversions, decimal to percentage, percentage to decimal. Practise exam-style problems and check your method.

fraction to decimalcommon conversionsdecimal to percentagepercentage to decimalfraction to percentagepercentage to fraction
GCSE Foundation70 questionsStep-by-step solutions
Question 1
1 markeasy
Write 12\frac{1}{2} as a decimal.
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Worked solution

  1. Turn the fraction into a division

    12=1÷2\frac{1}{2} = 1 \div 2

    A fraction bar just means 'divide the top number by the bottom number'.

  2. Work out the division

    1÷2=0.51 \div 2 = 0.5

    Dividing gives 0.50.5. This is one of the conversions worth learning by heart.

  3. State the answer

    0.50.5

    So 12=0.5\frac{1}{2} = 0.5 exactly.

Answer
0.50.5
Question 2
1 markeasy
Write 310\frac{3}{10} as a decimal.
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Worked solution

  1. Turn the fraction into a division

    310=3÷10\frac{3}{10} = 3 \div 10

    A fraction bar just means 'divide the top number by the bottom number'.

  2. Work out the division

    3÷10=0.33 \div 10 = 0.3

    Dividing gives 0.30.3. This is one of the conversions worth learning by heart.

  3. State the answer

    0.30.3

    So 310=0.3\frac{3}{10} = 0.3 exactly.

Answer
0.30.3
Question 3
2 marksintermediate
A jug is 34\frac{3}{4} full. What percentage of the jug is full?
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Worked solution

  1. Percent means 'out of 100100'

    34×100\frac{3}{4} \times 100

    To change a fraction into a percentage, multiply it by 100100.

  2. Multiply the fraction by 100100

    3×1004=3004=75\frac{3 \times 100}{4} = \frac{300}{4} = 75

    Working out the multiplication gives 7575.

  3. Attach the percent sign

    75%75\%

    Writing the percent sign shows this is a number out of 100100.

  4. Check with a benchmark

    75%  ?  50%75\% \; ? \; 50\%

    The fraction is bigger than a half (0.50.5), and the percentage is on the matching side of 50%50\%.

  5. Why multiplying by 100100 works

    1=100%1 = 100\%

    One whole is 100%100\%, so a fraction of a whole is that same fraction of 100%100\%.

  6. State the percentage

    75%75\%

    So 34=75%\frac{3}{4} = 75\%.

Answer
75%75\%
Question 4
4 markshard
Show that 58=62.5%\frac{5}{8} = 62.5\%.
Show worked solution

Worked solution

  1. State what must be shown

    58=62.5%\frac{5}{8} = 62.5\%

    We must prove the fraction equals the percentage exactly.

  2. Change the fraction to a decimal

    58=6251000=0.625\frac{5}{8} = \frac{625}{1000} = 0.625

    Scaling 5/85/8 to 625/1000625/1000 shows the decimal is 0.6250.625.

  3. Multiply the decimal by 100100

    0.625×100=62.50.625 \times 100 = 62.5

    Multiplying by 100100 turns the decimal into a percentage.

  4. Attach the percent sign

    0.625=62.5%0.625 = 62.5\%

    So the percentage is 62.5%62.5\%.

  5. Conclude

    58=62.5%\frac{5}{8} = 62.5\%

    The fraction and the percentage are exactly equal, as required.

  6. Check the two forms match

    58=62.5%\frac{5}{8} = 62.5\%

    Both sides describe exactly the same amount, just written differently.

  7. Sense check

    same position on a number line\text{same position on a number line}

    Equal values sit at the same point on a number line, which these do.

  8. Reflect on the method

    convert, then compare\text{convert, then compare}

    Turning both sides into one common form is the reliable way to prove an equivalence.

  9. Restate the conclusion

    58=62.5%\frac{5}{8} = 62.5\%

    The statement is shown to be true.

  10. Check the two forms match

    58=62.5%\frac{5}{8} = 62.5\%

    Both sides describe exactly the same amount, just written differently.

Answer
58=0.625=62.5%\frac{5}{8} = 0.625 = 62.5\%
Question 5
5 markschallenging
Write 87.5%87.5\% as a fraction in its simplest form.
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Worked solution

  1. Percent means 'out of 100100'

    87.5%=87.510087.5\% = \frac{87.5}{100}

    A percentage is a number out of 100100, so write it as a fraction over 100100.

  2. Clear the decimal from the fraction

    87.5100=87.5×10100×10=8751000\frac{87.5}{100} = \frac{87.5 \times 10}{100 \times 10} = \frac{875}{1000}

    Multiply top and bottom by 1010 so there is no decimal left in the fraction.

  3. Find the highest common factor

    HCF of 875 and 1000=125\text{HCF of } 875 \text{ and } 1000 = 125

    The biggest number dividing both 875875 and 10001000 is 125125.

  4. Divide top and bottom by the HCF

    875÷1251000÷125=78\frac{875 \div 125}{1000 \div 125} = \frac{7}{8}

    Dividing top and bottom by the same number simplifies without changing the value.

  5. Check by converting back

    78=87.5%\frac{7}{8} = 87.5\%

    Turning the fraction back into a percentage returns the value we started with.

  6. Check the size makes sense

    780.875\frac{7}{8} \approx 0.875

    The percentage is bigger than a half (0.50.5) of the whole, which the fraction agrees with.

  7. Write it as a decimal too

    87.5%=0.87587.5\% = 0.875

    The same amount as a decimal is the percentage divided by 100100.

  8. Why over 100100

    100%=1100\% = 1

    Because 'per cent' literally means 'per hundred', every percentage starts life over 100100.

  9. Watch a common slip

    87.5%87.51087.5\% \ne \frac{87.5}{10}

    The denominator is 100100, not 1010; per cent means per hundred.

  10. Cancel in stages if it helps

    875100078\frac{875}{1000} \to \frac{7}{8}

    You can cancel with smaller factors step by step instead of finding the HCF at once.

  11. Say it in words

    78\frac{7}{8}

    Reading the fraction aloud keeps its meaning clear.

  12. Real-world use

    78\frac{7}{8}

    Sale signs and statistics often need turning from a percentage into a fraction.

  13. Exam tip: simplest form

    78\frac{7}{8}

    Always cancel fully; the simplest form is usually where the mark sits.

  14. Double-check the cancelling

    78\frac{7}{8}

    Confirm the top and bottom share no further common factor.

  15. State the simplest form

    78\frac{7}{8}

    So 87.5%=7887.5\% = \frac{7}{8} in its simplest form.

Answer
78\frac{7}{8}

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