Number – fractions (including decimals)
Decimal place value
Say what each digit is worth in a decimal number.
The columns of a number keep going past the ones. To the left of the decimal point they get ten times bigger each step; to the right they get ten times smaller. So after the ones come tenths, then hundredths, then thousandths.
The rule
The decimal point never moves. It marks where the whole numbers stop and the parts begin, and every digit is worth whatever column it stands in.
Worked example
In 3.47, what is the 7 worth?
Name the columns after the point: 4 is in the tenths column, 7 is in the hundredths column.
Counting outwards from the point is what keeps the columns straight.
Have a play
This line runs from 0 to 1 in tenths. Look at where each tenth falls, and how much of the way along 0.7 really is.
Tap anywhere on the line.
Watch out
A longer decimal is not automatically a bigger one. 0.45 has more digits than 0.5, but 0.5 is the larger number, because five tenths beats four tenths before the hundredths are even looked at.
Try it together
Let us compare 0.6 and 0.58 together.
Compare column by column from the left, exactly as you would with whole numbers.
1.How many tenths does 0.6 have?
Have a go
Have a go on your own: how many hundredths are the same as 0.7?
Hint: Each tenth is worth ten of them.
Ready to practise?
Eight questions on what you have just read. Nothing is timed, and you can play as many times as you like.