Past the ones

About this video

A decimal is place value carried on past the ones. Each place to the left is worth ten times more, so each place to the right is worth ten times less: after the ones come the tenths, then the hundredths. The decimal point marks where the ones end. This short animation lays out the places and writes 2.7: two in the ones place, seven in the tenths place.

So 2.7 means two whole ones and seven tenths of another, which the video shows as two whole bars and a third bar cut into ten equal parts with seven shaded. On the number line, 2.7 sits between 2 and 3, at the seventh of the ten small steps between them. Some decimals are old friends: 0.5 is five tenths, which is a half, and 0.25 is twenty-five hundredths, which is a quarter. Last, the video compares 0.8 and 0.75. 75 looks bigger than 8, but decimals are compared place by place from the left, like whole numbers: 8 tenths beats 7 tenths, so 0.8 is bigger. This video goes with the Tenths and the Decimal Point lesson of Numbers Level 1 on Knaph.

Transcript

1. 0:00What does the point in two point seven mean?
2. 0:04Place value carries on past the ones. Tenths, then hundredths, each ten times smaller.
3. 0:10Two point seven is two ones and seven tenths.
4. 0:16On the number line, it sits between two and three.
5. 0:21Nought point five is a half. Nought point two five, a quarter.
6. 0:26Which is bigger? Compare from the left. Eight tenths wins.
7. 0:31The point marks where the ones end.