Significant Figures and Standard Forms

What is Significant Figure?

In measurement, significant figures indicates the certainty of the measurement. As the number of significant figures increases, the certainty of the measurement increases. In other words, we are more certain about what we have measured.

Similar sound. Different mean.

Practise or practice?

What is the correct spelling: practise or practice?

It depends on which version of English you’re using: in British English usage, the noun is practice and the verb is practise. In American English usage, both the noun and the verb are spelled (or spelt, in British English) as practice.

Sample sentences:

• Your coach phoned to say there will be a team practice in the gym tomorrow after school.
• He practised his presentation for hours to get it perfect.
• This book has some practice tests for your exam.

An expression with practice: practise what you preach – it means to do the things that you advise others to do.

When used in connection with lawyers and doctors, practice also means the work that they do and the place where they work. Sample sentence:

Joe has a very successful legal practice in New York.

They’re, their or there?

These three words are often used incorrectly too, just like it’s and its, even by native speakers. Again, it’s not very difficult to remember which is correct when.

They’re is the short form of they are:

My parents have gone on holiday and they’re in France today.
When students like a teacher, they’re more likely to do well in the subject he or she teaches.

Their is a possessive word, just like its or my:

My children always leave their toys all over the place.
The dogs ran towards their master.

There is an adverb of place; it means in that place. Think of it as an answer to the question “where?”. Here are some sample sentences:

We didn’t want to go there, but we had to.
Why did you put my book there?

Here’s a sentence with all three words; note how they’re (!) used:

They’re there, and all their friends are with them.

It’s or its?

These two words are very often confused. A typical mistake is when somebody uses “its” instead of “it’s”, although the opposite often happens, too. Actually, it’s not very difficult to remember which is correct in a given situation:

you can only use it’s if it is the short form of it is or it has (been). Here are some examples:

When you go abroad, it’s a good idea to take a guidebook with you.
(… it is a good idea…)

Don’t worry, it’s been like this for a long time.
(… it has been like this…)

Are you telling me that it’s my fault?
(… it is my fault?)

The box was hidden in an attic during the war and it’s been there until today.
(… it has been there…)

Its is a possessive word, just like my or your; it means that something owns something or something belongs to it. Examples:

The car was badly damaged but its driver escaped unhurt.
The dog went back to its house.
The house and its garden are a popular tourist attraction.