In the IELTS Listening Test, you are often required to listen for the next answer while writing down the answer to the previous question. It is one of the measures of effective listening – the examiners want to find out if you can comprehend what is said while attempting another task at the same time. This further tests your listening ability in English.
To write down the answers more quickly, write only the first two or three letters of the answer that you hear. This shorthand approach is effective in a gapfill listening task because some of the answers may come in quick succession, especially at the beginning of the gapfill passage. You can complete the words during the short period of time given to you after the passage has finished. You are very likely to remember what the letters mean because they are the first letters of words you have recently heard in context.
This method can enable you to return quickly to giving your whole attention to listening for the next answer. However, it does require some practice. Note that you would not try to use this method to remember numbers, but with word answers you can almost always remember the words again. Then, all you need to do is give the correct grammatical form of the answers.