Multiplying and dividing decimals
Multiply without the comma and count the places, and divide by first making the divisor a whole number. Read one step, play with it, then tap “I understand this”.
Tenths times tenths
0,3 × 0,4 means 0,3 of 0,4. The answer is smaller than both numbers, because you take a part of a part.
The hundred grid
Change the two numbers and look at the green overlap.
Multiply without the comma, then count the places
Multiply the numbers as if there are no commas. Then count how many digits come after the comma in the question. That many digits go after the comma in the answer.
See how it works
Tap “Another one” for a new sum.
When you multiply by a number smaller than 1 (like 0,5), the answer gets smaller.
0,3 is 3 tenths and 0,4 is 4 tenths. A tenth of a tenth is a hundredth, just like on the hundred grid: 3 × 4 = 12 hundredths = 0,12. One place + one place = two places.
Dividing by a whole number
Divide as always. The comma in the answer sits straight above the comma in the sum: 7,5 ÷ 3 = 2,5.
Think in tenths: 7,5 is 75 tenths. 75 tenths ÷ 3 = 25 tenths = 2,5.
Dividing by a decimal
First make the divisor a whole number: multiply both numbers by 10 (or 100). The answer does not change: 4,8 ÷ 0,6 = 48 ÷ 6 = 8.
The division machine
Choose a kind of sum and tap “Another one”.
If you multiply only the divisor by 10, your answer is 10 times too small. Always do the same to both numbers.
Dividing asks: how many times does 0,6 fit into 4,8? Make both 10 times bigger, and 6 still fits into 48 exactly as many times. It is like zooming in on a picture: everything gets bigger, but the relationship stays the same.
Your turn
Multiply and divide
Type the answer. Use the comma button.
Check yourself
- Multiply: multiply without commas, then count the places after the comma in the question.
- Divide by a whole number: comma straight above the comma.
- Divide by a decimal: multiply both by 10 or 100 until the divisor is whole.
- Always estimate: is your answer about right?
Write these points in your maths book. Read them again the night before the test.
Quick questions
Tap an answer. If you get one wrong, read why and go back to that step. You get new questions every time.
You ticked all 5 steps! Now you are ready for the quiz.- Practice sheet for this classQuestions + memo · 2 A4 pagesPractice sheet
- Numbers9 pages · PDFPaperMemo
Ready for more? The Grade 7 decimals quiz gives you new sums every time.
- One step a day is enough. Ten calm minutes work better than an hour the night before the test.
- Use shop prices: “Bananas cost R24,90 per kg. What does 0,5 kg cost?” Let your child estimate first, then work it out.
- Ask your child to tell you the rule in their own words. If they can explain it, they understand it.
- The ticks (“I understand this”) are saved on this device only. We never ask for names or emails.
Follows CAPS for Grade 7 Maths. Always check your teacher’s notes and textbook too.