WorksheetsAbout this worksheet
Decimal sums written in columns, with the points one under the other. The method is the same as for whole numbers; the only new rule is to keep the decimal points in a line and to put the point in the answer straight below them.
What this skill is
A decimal carries place value to the right of the ones. The first place after the point is tenths and the second is hundredths, so 4.75 is 4 ones, 7 tenths and 5 hundredths. Because each place is still ten times the one on its right, adding and subtracting work exactly as for whole numbers, as long as like places stand under each other.
A worked example
Take 14.6 − 8.75.
- Give both numbers the same number of decimal places: 14.6 is 14.60.
- Write 8.75 under 14.60 with the points in a line.
- Hundredths: 0 − 5 needs borrowing. 10 − 5 = 5, and the 6 tenths become 5.
- Tenths: 5 − 7 needs borrowing. 15 − 7 = 8, and the 4 ones become 3.
- Ones and tens: 13 − 8 = 5.
The answer is 5.85. Check: 5.85 + 8.75 = 14.60.
Tips for parents and teachers
- If one number has fewer decimal places, write zeros to fill the gap: 4.5 is the same as 4.50.
- Estimate first with whole numbers. 12.8 + 7.3 must be near 20.
- Money is the easiest way in: ₹12.50 + ₹7.25 is a decimal sum the child already understands.
How to use this sheet at home and in class
- At home: begin with one decimal place and addition. Measuring with a ruler in centimetres gives real numbers such as 12.4 and 7.8 to add.
- In class: let children estimate each answer to the nearest whole number in the margin before working. A wrong place for the point is then caught at once.
- Choose "Two (hundredths)" and "Mixed" for classes 5 and 6, and link the sheet to rupees and paise.
Mistakes to watch for
- Lining the numbers up on the right, as for whole numbers, when they have different numbers of decimal places.
- Leaving the point out of the answer, or putting it by guesswork. It goes straight below the other points.
- Believing that 4.50 is bigger than 4.5 because it looks longer. They are the same number.
What to try next
- Indian money worksheets: decimals as rupees and paise.
- Percentage worksheets: the next step in classes 5 to 7.
- Unit conversion worksheets: metres and centimetres, kilograms and grams.