Type the whole expression, then press equals
Most modern scientific calculators, including ours, read a full expression instead of working one key at a time. That's good news. You can type 3 + 4 x 2 exactly as it's written and get 11, because the calculator applies the order of operations for you.
It also means the calculator does what you typed, not what you meant. If your expression is missing a parenthesis, you'll get a confident wrong answer. So the first habit to build is reading the screen before you press equals.
Use parentheses more than you think you need
The classic mistake is a fraction with a sum on top or bottom. To work out (12 + 8) / 4, you have to type the parentheses. Without them, 12 + 8 / 4 gives 14 instead of 5.
The same goes for exponents with more than one term. 2^(3 + 1) is 16, while 2^3 + 1 is 9. And a square root of a sum needs brackets around the whole sum: sqrt(9 + 16) = 5, but sqrt(9) + 16 = 19. Extra parentheses never change a correct answer, so when in doubt, add them.
Negative numbers and powers
Calculators treat -3^2 as -(3^2), which is -9. Math teachers do too, but it surprises a lot of people. If you want negative three squared, type (-3)^2 and you'll get 9.
Use the ± key or a minus sign inside parentheses for negative inputs to functions as well. cbrt(-27) is -3, but sqrt(-4) is an error, because a negative number has no real square root.
Check DEG or RAD before every trig problem
This causes more wrong answers than anything else. In degree mode, sin(30) is 0.5. In radian mode, the calculator thinks you mean 30 radians and gives about -0.988.
A quick test: if the problem shows a degree symbol, use DEG. If the angle has pi in it, like pi/6, use RAD. Inverse functions follow the same switch, so asin(0.5) gives 30 in DEG and about 0.5236 in RAD.
Real use looks like this. A 5 m ladder leaning at 40 degrees reaches a height of 5 x sin(40), about 3.214 m, but only in DEG mode.
EXP is not the same as ^
The EXP key (sometimes labelled EE or x10^x) means "times 10 to the power of". Type 3 EXP 8 and you've entered 3 x 10^8. Typing 3 x 10 ^ 8 gets the same value, but it's easy to slip, and typing 10 EXP 8 gives 10 x 10^8, which is ten times too big.
Use ^ for ordinary powers and EXP only for scientific notation. For example, 3e8 x 2e-3 = 600,000.
log vs ln, and chaining answers with Ans
log means base 10 and ln means base e. Chemistry pH problems and decibels use log. Growth, decay and continuous interest use ln. Mixing them up gives an answer that's off by a factor of about 2.3.
For multi-step problems, don't copy rounded decimals by hand. Press Ans to reuse the last answer at full precision. Our scientific calculator also keeps your last 12 calculations in history, so you can go back and check a step.
Frequently asked questions
What's the first thing to check on a scientific calculator?
The angle mode. If it's set to radians when your problem uses degrees, every trig answer will be wrong.
How do I type a fraction on a scientific calculator?
Use the divide key and parentheses. For (3 + 5) / 2, type the parentheses so the whole top is divided.
What does the EXP key do?
It means times 10 to the power of. 3 EXP 8 is 3 x 10^8. Use it for scientific notation, not ordinary powers.
When should I use log versus ln?
Use log for base-10 problems like pH and decibels. Use ln for natural growth and decay, where e is the base.
Why shouldn't I retype answers between steps?
The screen shows a rounded number. Retyping it drops digits, and small errors grow over several steps. Ans keeps the full value.
References
These sources support the method or guidance used for Scientific Calculator. Verify time-sensitive rules at the source.
Try the calculator
Open Scientific Calculator, enter your scenario, and compare its supporting rows with this guide's method and checks.