This function is usually found by pressing SHIFT . To find 24% of £32, press 3224 and the calculator will display 7.68
To convert the fraction \displaystyle \frac{3}{4} to a percent, press 34 and the calculator will display 75.
To increase £12 by 4% press 124 and the calculator will display 12.48.

Or +/-. Be clear about the difference between this button and the "take away" button.
In a calculation like 6 - -7 the first - means "take away" and the second means "negative 7".
You should enter 67 to get 13 as your answer.

A common source of confusion occurs when you want to find the square of a negative number, for example, -3². Does this mean -3 x -3 = 9 or -1 x 9 = -9? If you enter these instructions:
3 or
3
you get -9. If you want the calculator to work out -3 x -3, then you should enter
3 or
3
Although it is true that calculators do not always say Error! if you use when you should have used , it is good practise to do so. Often calculators will insert automatically if you use wrongly, and then give you totally the wrong answer.

These two buttons work out squares and square roots, for example 3.5² is found by entering 3.5 to obtain 12.25. The square root of 256 is found by entering 256 to get 16.
You will need these buttons when solving problems using Pythagoras's theorem. If the two shorter sides of a right-angled triangle are 4 cm and 7 cm, then the longest side (the hypotenuse) can be found by entering 47 to get 8.062257748

Many recent calculators also have a button for working out cubes. For example 2 will give 8 as the answer.

Or x^y. You use this to work out powers or indices. To work out 3⁴, enter 34 and you will get 81. For 2⁶ enter 26, which is 64. For 5^-1 you should enter 51 and get 0.2.
To work out 2.1² you could enter either
2.12 or 2.1

What is 6⁰?

You can add, subtract, multiply and divide fractions with this button, and simplify fractions and convert between decimal and fraction form.
To work out \displaystyle \frac{2}{5}+\frac{3}{4} you should enter 2534 and your calculator should display 1320 which means \displaystyle 1 \frac{3}{20}. If you press again the calculator will convert this fraction to the decimal 1.15.
To work out \displaystyle \frac{3}{5} \times \frac{1}{6} you should enter 3516 and your calculator should display 110 which means \displaystyle 1 \frac{1}{10} and shows that your answer has been automatically simplified for you.
You can convert any decimal to a fraction with this button. To convert 0.126 you enter 0.126 and 63500 is displayed.

The area of a trapezium is given by the formula \text{area} = \frac{1}{2}(a+b)h. When a = 3 , b = 4 and h = 7, enter
12347
and your calculator will display 24.5.

Or EE button. Use this to enter numbers in standard form.
For example, the number \displaystyle 6 \times 10^{13} is entered as 613.
So to work out 4.1 \times 10^{9} + 3.8 \times 10^8 you enter
4.193.88 to obtain the answer 4.48 \times 10^{9}

Many calculators now have an ANS buttons as well as an "=" button. The ANS button will recall the previous answer. These buttons can be used to repeat simple calculations over and over again (which is called iteration). For example, if this set of instructions is entered:
1223
then 9, 7.5, 6.75, 6.375 should be displayed.

These three buttons are use to find the sine, cosine and tangent of an angle. To find cos (30°) enter 30 and the calculator will display 0.866025403.
To find the angle whose tangent is 1.3, you use the tan^-1 function obtained by pressing SHIFT (or 2nd on some calculators) then .
So SHIFT1.3 will display 52.43140798.
Remember that your calculator must be set to DEG (not RAD or GRA) for this to work correctly.