Represent decimals to thousandths
Theory
Each place to the right of the decimal point is ten times smaller than the place before it: tenths, hundredths, then thousandths. This Year 5 maths page shows how to read and write decimals such as \(3.274\), find the place and value of any digit, partition a decimal by place value, and use thousandths in measurement (\(1\text{ mm} = 0.001\text{ m}\)).
The decimal point separates the whole number from the parts of a whole. The places after it are tenths (\(0.1\)), hundredths (\(0.01\)) and thousandths (\(0.001\)).
The place of a digit is the column it is in. Its value is how much it is worth there. In \(3.274\), the \(7\) is in the hundredths place and its value is \(0.07\).
To partition a decimal, write it as the sum of the values of its digits: \(3.274 = 3 + 0.2 + 0.07 + 0.004\). A zero digit adds nothing, so it gets no part.
To read a decimal, say the whole number, then “and”, then the digits after the point as a number of the last place: \(1.608\) is one and six hundred and eight thousandths.
In measurement, \(1\text{ m} = 1000\text{ mm}\), \(1\text{ L} = 1000\text{ mL}\) and \(1\text{ kg} = 1000\text{ g}\), so one thousandth of a metre, litre or kilogram is \(1\) mm, \(1\) mL or \(1\) g.
Each place is ten times smaller than the place to its left:
How to find the value of a digit
- Count places after the decimal point: 1st tenths, 2nd hundredths, 3rd thousandths.
- Write the digit in that place with zeros before it: a \(9\) in the thousandths place is worth \(0.009\).
How to write a decimal from words
- Find the last place named (tenths, hundredths or thousandths).
- Write the number so that its last digit lands in that place, filling gaps with zeros.
(i) four thousandths
(ii) fifty-six thousandths
(iii) three hundred and twelve thousandths
| \(4 \text{ thousandths}\) | \(=\) | \(0.004\) |
| \(56 \text{ thousandths}\) | \(=\) | \(0.056\) |
| \(312 \text{ thousandths}\) | \(=\) | \(0.312\) |
(i) \(0.004\)
(ii) \(0.056\)
(iii) \(0.312\)
The \(9\) is the third digit after the decimal point.
The thousandths place; its value is \(0.009\).
| \(8.62\) | \(=\) | \(8 + 0.6 + 0.02\) |
\(8 + 0.6 + 0.02\).
| \(6 + 0.04 + 0.009\) | \(=\) | \(6.049\) |
\(6.049\).
The digits after the point are \(608\), ending in the thousandths place.
One and six hundred and eight thousandths.
(ii) A jug holds \(2.35\) L. How many millilitres is that?
| \(0.375 \times 1000\) | \(=\) | \(375\) |
| \(2.35 \times 1000\) | \(=\) | \(2350\) |
(i) \(375\) mm
(ii) \(2350\) mL
| \(0.8 \times 1000\) | \(=\) | \(800\) |
\(80\) mm is only \(0.08\) m, so it is not equal to \(0.8\) m.
In \(0.3\) the \(3\) is in the tenths place; in \(0.03\) it is in the hundredths place.
The values are \(0.3\) and \(0.03\). \(0.3\) is ten times as big.
Common pitfalls
Frequently asked questions
What is a thousandth?
One part when a whole is split into \(1000\) equal parts. It is written \(0.001\).
How do you find the value of a digit in a decimal?
Find its place, then write the digit in that place: in \(7.519\) the \(9\) is worth \(0.009\).
How do you partition a decimal?
Write it as the sum of the values of its digits: \(8.62 = 8 + 0.6 + 0.02\).
How do you say 1.608?
One and six hundred and eight thousandths.
How many millimetres are in 0.375 m?
\(375\) mm, because \(1\) m is \(1000\) mm.