Units or ones? For many years children were taught about hundreds, tens and units (HTU) and our worksheets used this layout at the top of columns when adding or subtracting. However, in the latest Mathematics Programme of Study the term ‘ones’ is used in place of units. This has subsequently led to some debate about how columns are labelled where it is impossible to write the whole word above a column. H for hundreds, T for tens and U for units was the old method, but to replace U with an O (for ones) does not work as it is too close to a zero. The consensus now seems to be to label them 100s, 10s and 1s. We have changed many of our worksheets to reflect this change in terminology and will continue to update them as necessary.