Parent guide · 6 min read
Fractions to decimals for kids: divide the top by the bottom
Converting a fraction to a decimal looks like a separate skill with its own rules, and children often try to memorise a chart of answers instead. There is really one idea underneath: a fraction bar means "divided by", so 3/4 is 3 ÷ 4. Three methods follow from that, and which one is quickest depends on the bottom number. This guide sets them out with checked examples and the slips that come up most.
Try this tonight
5 things you can do at home
Say what the fraction bar means
Point at 3/4 and ask "what is another way to write that with a division sign?" The answer, 3 ÷ 4, is the whole method. A child who sees the bar as "divided by" no longer needs a separate rule for each fraction.
Learn six anchors by heart
Knowing 1/2 = 0.5, 1/4 = 0.25, 3/4 = 0.75, 1/5 = 0.2, 1/10 = 0.1 and 1/8 = 0.125 gives a child something to check every other answer against. A result for 5/8 should land a little above 0.5, since 4/8 is exactly one half.
Try the "make it a tenth or hundredth" method first
Ask whether the bottom number can be multiplied up to 10, 100 or 1000. 2 and 5 reach 10; 4, 20 and 25 reach 100; 8 reaches 1000. If so, no long division is needed, only multiplying the top and bottom by the same number.
Use a written division when the shortcut does not fit
For 5/8, divide 5 by 8 by adding a decimal point and zeros: 5.000 ÷ 8. Do it on paper with your child, one line at a time, and keep the decimal point in the answer directly above the one inside the division.
Finish by estimating
Ask "is it more or less than a half?" before and after converting. If 5/8 came out as 0.58 or 8.5, the estimate flags it at once, because the answer should be just over 0.5.
Why dividing works
A fraction such as 3/4 means "3 of 4 equal parts of one whole". Sharing 3 whole things equally between 4 people gives each person the same amount, which is also 3/4 of one thing. So 3 ÷ 4 and 3/4 are two ways of writing the same number, and the decimal 0.75 is simply the answer to that division written with place value.
This is also why the order matters. The smaller number is on top in a fraction less than one, so the division is small ÷ large and the answer is below 1. Many mistakes come from dividing the wrong way round, 4 ÷ 3, which gives 1.33… instead.
Worked example: two methods side by side
Method 1, equivalent fractions. Convert 7/20. 20 × 5 = 100, so multiply the top by 5 too: 7 × 5 = 35. That gives 35/100, which is 0.35. Check by multiplying back: 0.35 × 20 = 7. ✓
Method 2, written division. Convert 5/8. 5 ÷ 8 does not go in whole, so write 5.000 and divide. 50 ÷ 8 = 6 remainder 2, so the first digit after the point is 6. Bring down a zero: 20 ÷ 8 = 2 remainder 4, so the next digit is 2. Bring down another: 40 ÷ 8 = 5 remainder 0, so the last digit is 5. 5/8 = 0.625. Check: 0.625 is a little above 0.5, as expected, and 0.625 × 8 = 5. ✓
The same division also answers 3/8 (0.375) and 7/8 (0.875). Seeing that these all come from one process, rather than being separate facts to learn, is what makes the topic feel smaller.
When the decimal never ends
Try 5/6 with the same division: 50 ÷ 6 = 8 remainder 2, then 20 ÷ 6 = 3 remainder 2, then 20 ÷ 6 = 3 remainder 2 again. The same remainder keeps coming back, so the digit 3 repeats forever: 5/6 = 0.8333… Likewise 1/3 = 0.333… and 2/3 = 0.666…
A repeating decimal is not a mistake or a calculator glitch. It happens when the remainder never reaches 0. Children are usually asked to round (2/3 ≈ 0.67) or to put a bar over the repeating digit. If a division keeps giving the same remainder, that is the sign to stop and say it repeats.
The usual slips
Writing the top and bottom either side of the point is the most common one: 3/4 becomes 3.4 or 0.34. Ask for the estimate. 3/4 is three quarters of a whole, so the decimal must be below 1 and above 0.5.
The second is reading 1/8 as 0.8. One eighth is a small piece, much less than a half, so 0.8 cannot be right; it is 0.125. The third is losing the zero in a case like 3/50 = 6/100 = 0.06, not 0.6. Each place has to be filled, even with a zero.
Signs it’s time for outside help
When home help has done what it can
- Writes 3/4 as 3.4 or 0.34, putting the two numbers on either side of the point.
- Divides the bottom by the top, or cannot say which way round the division goes.
- Has to start the written division from scratch every time, with no anchor facts.
- Thinks a repeating decimal means a wrong answer.
- Has the same trouble with long division, so the conversion fails at the division step.
Questions parents ask
FAQ
What age do children learn to convert fractions to decimals?
Fractions with a bottom number of 10 or 100 are written as decimals in US Grade 4 (about ages 9–10). Converting any fraction by dividing usually comes in Grade 5 and later, about ages 10–12.
What is the quickest way to convert a fraction to a decimal?
If the bottom number goes into 10, 100 or 1000, make an equivalent fraction with that bottom and read off the decimal: 7/20 = 35/100 = 0.35. Otherwise divide the top by the bottom.
Why does 1/3 give 0.333… forever?
When you divide 1 by 3, the remainder is 1 again at every step, so the same digit 3 keeps coming out. The decimal never ends, so it is written with a bar over the 3 or rounded, for example 0.33.
How do I convert a mixed number such as 2 1/4?
Keep the whole number and convert only the fraction: 1/4 = 0.25, so 2 1/4 = 2.25. There is no need to turn it into an improper fraction first.
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