## #The mental cost of attention

Determine how much attention someone needs to give your content. For example, full attention, partial attention or little attention. A security update might need someone’s full attention, while an ad for a new product feature isn’t urgent.

There’s now a mental cost to everything we do. We have to define what we care about and what we want to pay attention to.

Time is the most important currency and people want to steal it with ads, pop ups, marketing and so on. Keeping people unnecessarily hooked for more time than it’s worth.

As designers, we can respect time and focus by rounding up numbers and removing unnecessary content.

## #Avoid decimals unless it’s money

People with dyscalculia or those who feel anxious about money make mistakes like:

withdrawing the wrong amount of cash

sending the wrong amount of money to someone

not spotting mistakes on bills and receipts

overpaying for things

How you display money is important. For example, £10 and £10.00 is the same amount. But for people with dyscalculia or Irlen syndrome, the amount easily looks like £100 (one hundred).

If you must display exact amounts of money, like £7.56, that’s OK.

If your service deals with large numbers, like millions or billions. Write the number in words, like 6 million and not £6,000,000.

Getting o and 0 mixed up is a common error when dealing with money. Especially since they’re next to each other on a keyboard. Using a slashed zero (zero with a line through it) helps people distinguish between the letter o and the number 0. Although some people might read a slashed zero as the number 8. Choose a good font.

Avoid using 0 and 1 if they could cause confusion with letters. For example, passcodes and reference numbers where 1 might be confused with I or L. Lowercase a looks like o from far away.

The readability guidelines have good info on presenting numbers, as does the GOV.UK style guide money section.

Use the £ symbol: £75

Do not use decimals unless pence are included: £75.50 but not £75.00

Do not use ‘£0.xx million’ for amounts less than £1 million.

Write out pence in full: calls will cost 4 pence per minute from a landline

## #When to use fractions and percentages

We use maths in daily life, like cooking, shopping, organising a trip, arranging something, dealing with finances or determining the outcome of a medical procedure.

But 1 in 5 adults has forgotten how to do fractions and percentages. And Low numeracy is a long term problem for the UK.

And if you’re dyscalculic, you might struggle:

counting backwards and counting in steps

sequencing and recognising patterns

sorting out directions like left, right, high, low and depth

understanding quantities

telling the time

identifying large or small numbers in a list

making sense of money and estimating quantities

remembering maths without counting

visual and spatial orientation

Fractions are tricky for dyscalculics because:

thinking about 2 numbers in relation to each other is not easy

it’s easy to make mistakes like reversing the numbers when copying fractions

The NHS service manual says it’s better to say ‘1 in 2’ or ‘half’ than 50%. And ‘1 in 7 people’ rather than 14.3%.

Consider your audience when communicating statistics, especially about health, since a doctor may have different needs than someone using the NHS website.

Or it could be something simple, like the weather. If there’s a 30% chance of rain tomorrow. Do you think:

it will rain 30% of the time

it will rain in 30% of the area, or

there’s a 30% chance that it will rain based on the weather conditions

The National Weather Service defines the probability of rain as the likelihood of occurrence (expressed as a percentage) of rain at any point in the forecast area.

30% of rain tomorrow means when the weather conditions are like today, rain will fall the next day, in 3 out of 10 cases.

Explaining what fractions and percentages mean is about giving people informed choices about decisions that affect their life, even about the weather.