Write per cent, not "percent". If using the % sign, don't put a space between it and the digit:
Of the 5000 people who answered the survey, 10% (or 10 per cent) were French.
58%, 90%, etc.
When calculating percentages, beware the "rose by/fell by X%" construction: an increase from 3% to 5% is a 2-percentage-point increase or a 2-point increase, not a 2% increase
Never use the "per thousand" symbol, ‰
Lower case. Not "Petabyte" or, worse, "PetaByte"
A unit of information equal to one thousand million million (1015) or, strictly, 250 bytes.
Almost overnight, companies are transitioning from storing gigabytes of data to managing terabytes, and even petabytes, of information.
Capital P, lower case h, capital D. Note the lack of punctuation.
Jenny will defend her PhD thesis this year.
Use only 2D pie charts, and label each slice with its corresponding percentage.
Never use 3D pie charts. They misrepresent data.
The important parameter of a pie chart is area. If the pie is represented in 3D, the foreshortening skews the area of each slice and the chart becomes misleading.
In the example below, the 1% slice is at the "back" of the chart – the perspective imposed makes that slice look smaller. Bringing this slice to the front would similarly skew the look of the chart, making the 1% slice look bigger.
Or PIN number (although PIN stands for personal identification number, the tautology is in near universal use), not Pin or pin number
Not "pi-meson"
When quoting country, state or county names after the name of a town, set commas before and after:
New results were announced at the conference in Osaka, Japan, last week.
It is not necessary to say that London is in the UK. For all other UK cities, spell out explicitly that they are in the UK.
A team of physicists from Manchester in the UK reported that…
Not "policeman"
