Which decimal is bigger?

Hello, and welcome to Myriora Maths! Which is bigger: zero point five, or zero point four five? Lots of people get this wrong. By the end of this video, you won't!

When do we need this? Prices are decimals! Here's one pound fifty, and one pound five. Which costs more? One pound fifty is a hundred and fifty pence. One pound five is only a hundred and five pence. So one pound fifty costs more.

First, what does zero point five mean? Take one whole bar, and cut it into ten equal pieces. Each piece is one tenth. Zero point five means five tenths. That's half the bar.

Now cut every tenth into ten tiny pieces. That makes a hundred tiny pieces altogether. Each one is a hundredth. Zero point four five means four tenths, and five hundredths. That's forty-five tiny pieces.

Let's put them side by side. Zero point five is five tenths: that's fifty tiny pieces. Zero point four five is forty-five tiny pieces. Fifty is more than forty-five. So zero point five is bigger!

Here's the quick way. Line up the decimal points, and look at the tenths first. Zero point five has five tenths. Zero point four five has only four tenths. Five tenths beats four tenths, so zero point five is bigger. The hundredths don't matter here, just like the ones didn't matter when the tens were different.

Another trick: put a zero on the end. Zero point five is the same as zero point five zero. Fifty hundredths is the same as five tenths! Now both numbers have two digits after the point: fifty, and forty-five. Easy!

Let's try one together. Which is bigger: zero point three, or zero point two nine? Line up the points, and look at the tenths. Say your answer out loud!

Zero point three has three tenths. Zero point two nine has only two tenths. So zero point three is bigger. Well done if you said zero point three!

Remember this rule? With whole numbers, more digits means a bigger number. A hundred and twenty-three is bigger than thirty-two. But after the decimal point, that's not true! Zero point four five has more digits, but it's smaller than zero point five. So always line up the points, and look at the tenths first.

Here's a question that catches lots of people. Which is bigger: zero point eight, or zero point one two? Some people say zero point one two, because twelve is bigger than eight. But look at the tenths! Zero point eight has eight tenths. Zero point one two has only one tenth. So zero point eight is bigger.

Your turn! Which is the biggest: zero point seven, zero point six five, or zero point seven two? You've got fifteen seconds, or pause the video. Go!

Time's up! Zero point six five has only six tenths, so it's out. Zero point seven and zero point seven two both have seven tenths. So look at the hundredths. Zero point seven is zero point seven zero, and zero hundredths is less than two. So zero point seven two is the biggest!

Quick review. Line up the decimal points. Look at the tenths first, then the hundredths. Put zeros on the end if it helps. And after the point, more digits does not mean bigger! See you next time!