Video: KS2-M16 • Paper 1 • Question 20

0.9 ÷ 10 = _.


Video Transcript

0.9 divided by 10 equals what?

0.9 isn’t a multiple of 10. So how can we divide a decimal number like this by 10? This calculation is very quick to work out as long as we understand how numbers change when they’re divided by 10. To help us understand how the digits in 0.9 are going to change, let’s write it in a place value chart.

Zero ones and nine tenths, so what happens when a number of ones or a number of tenths is divided by 10? Let’s sketch a quick diagram to help us understand. This square represents one whole. That’s the same as the ones column in our place value chart. And if we divide that one whole into 10, the value becomes one-tenth. We know that the next column to the right in our place value chart are worth tenths. And so our ones digit moves one place to the right. Zero ones becomes zero tenths.

Now let’s look at what happens to the tenths digit. Again, we can use our diagram to help. What happens if we divide tenths by 10? Our value of tenths have a value of hundredths. And we can see that the hundredths place is again the next column along to the right. And so, our nine-tenths again shift one place to the right, and now have a value of nine hundredths.

And to complete our answer, we can write a zero in the ones place to act as a placeholder. So to find the answer to this question, we don’t need to draw place value charts or little diagrams of squares. We simply need to understand what happens to the digits in a number when we divide them by 10.

The place value chart and the diagram were just our way of reminding ourselves. When a number is divided by 10, the digit shift one place to the right. And so if we know this, then we know that nine-tenths become nine hundredths, which is something we can work out fairly quickly in our heads. 0.9 divided by 10 equals 0.09.

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