Why is my trigonometry answer wrong?

Angle mode, nine times out of ten. sin(30) is 0.5 in degrees and about -0.988 in radians. Check which mode is active before assuming the calculation is at fault.

Why does a simple sum show a long decimal?

Binary floating point cannot represent some decimal fractions exactly, so tiny rounding errors accumulate and surface at the far right of the answer. It is a property of the arithmetic every computer uses, not a defect in the calculation.

Is this the same as a Casio scientific calculator online?

It is not a Casio emulator, but it covers the functions students use most: sin, cos and tan in degrees or radians, ln and log, powers, roots, factorials, nPr and nCr. It has no statistics or matrix mode, so use the Statistics Calculator or the Matrix Calculator for those.

Scientific Calculator Online

A scientific calculator with trigonometry, logarithms, powers and roots, showing the expression you entered so a mistyped bracket is visible.

Browser tool

= 1025

angles in degrees

1025

How expressions are read

Only numbers, the listed functions, π, e and the operators + − × ÷ ^ ! % are accepted; the expression is parsed into a tree and evaluated — nothing is executed as code. ^ is right-associative and binds tighter than a leading minus (−2^2 = −4); 2(3+4) and 3π multiply implicitly; n! and % are postfix (50% = 0.5). Results show up to 12 significant digits; sin(180°) is snapped to exactly 0. Ans reuses the last result committed with = or Enter.

About Scientific Calculator

Trigonometry, logarithms, powers and roots, with the expression you entered kept on screen. That last part matters more than it sounds: most calculator errors are not arithmetic at all but a bracket in the wrong place, and a display showing only the answer hides exactly the thing that went wrong. A free online calculator, nothing to install, nobody to sign in as. Every result is produced by the browser.

How to use Scientific Calculator

Type the expressionOperator precedence is respected, so multiplication binds tighter than addition without needing brackets around it.
Check the expression before the answerIt stays visible. A mistyped bracket produces a confident wrong number, and this is where you catch it.
Mind the angle modeDegrees and radians give completely different answers from the same trigonometric input.

Precedence, and the brackets worth adding anyway

Multiplication and division bind tighter than addition and subtraction, and exponentiation tighter still, so 2 + 3 * 4 is 14 rather than 20. The rules are unambiguous and people still misread them at a glance, which is why adding brackets you do not strictly need is good practice: they cost nothing and they make the intent visible to whoever checks the working, including you tomorrow.

What it does not do

Floating-point arithmetic. Results can carry tiny representation errors, which is why 0.1 plus 0.2 is famously not exactly 0.3 in any language that uses it.
Very large and very small magnitudes lose precision at the edges of what a double can represent.

Scientific Calculator: questions people ask

Why is my trigonometry answer wrong?: Angle mode, nine times out of ten. sin(30) is 0.5 in degrees and about -0.988 in radians. Check which mode is active before assuming the calculation is at fault.
Why does a simple sum show a long decimal?: Binary floating point cannot represent some decimal fractions exactly, so tiny rounding errors accumulate and surface at the far right of the answer. It is a property of the arithmetic every computer uses, not a defect in the calculation.
Is this the same as a Casio scientific calculator online?: It is not a Casio emulator, but it covers the functions students use most: sin, cos and tan in degrees or radians, ln and log, powers, roots, factorials, nPr and nCr. It has no statistics or matrix mode, so use the Statistics Calculator or the Matrix Calculator for those.

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