Decimal Fractions
ICSE Class 6 · Mathematics · Chapter 15
What this chapter covers
- What a decimal fraction is
- Place value in decimals
- Changing fractions into decimals and decimals into fractions
- Adding and subtracting decimals
- Word problems on money, mass, length and temperature
Key points
- A decimal fraction is a fraction with denominator 10, 100, 1000 and so on, and it can be written with a decimal point.
- The places after the point are tenths, hundredths and thousandths, each one-tenth of the place on its left.
- A decimal is read digit by digit after the point: 5.36 is "five point three six".
- Like decimals have the same number of decimal places; zeros added at the right end do not change the value.
- To change a decimal into a fraction, write it over 10, 100 or 1000 and simplify.
- To change a fraction into a decimal, make an equivalent fraction with denominator 10, 100 or 1000.
- To add or subtract decimals, make them like decimals and line up the decimal points.
- In word problems, change all amounts to the same unit first: ₹1 = 100 paise, 1 m = 100 cm, 1 km = 1000 m and 1 kg = 1000 g.
Questions answered
Write (56)/(100) as a decimal, and write how you would read it aloud.
0.56, read as "zero point five six".
What is the place value of 4 in 27.849?
The 4 is in the hundredths place, so its place value is (4)/(100), or 0.04.
Write 5.208 in expanded form.
5 + (2)/(10) + (0)/(100) + (8)/(1000), which is 5 + 0.2 + 0.008.
Are 4.3 and 4.30 equal? Give a reason.
Yes. A zero at the right end of a decimal does not change its value, because (3)/(10) = (30)/(100).
Change 0.45 into a fraction in its simplest form.
0.45 = (45)/(100) = (9)/(20).
Change 2(3)/(5) into a decimal.
(3)/(5) = (6)/(10) = 0.6, so 2(3)/(5) = 2.6.
Find 14.5 - 6.78 + 3.2.
14.50 - 6.78 = 7.72, and 7.72 + 3.20 = 10.92.
Arjun has ₹200. He buys a notebook for ₹45.50 and a geometry box for ₹98.75. How much money does he have left?
He spends 45.50 + 98.75 = 144.25 rupees, and 200.00 - 144.25 = 55.75. So he has ₹55.75 left.