Scientific calculator for Windows

Write it the way it looks on paper

The calculator follows the usual order of operations: brackets first, then powers, then × and ÷, then + and −. So 3 + 4 × 2 is 11, and (3 + 4) × 2 is 14. A few details are worth knowing:

• Powers stack from the right. 2^3^2 means 2^9, which is 512, not 64.
• A minus sign in front waits for the power. −2^2 is −4. Write (−2)^2 to square a negative number and get 4.
• Numbers side by side multiply. 2π is 6.2831853072 and 3(4 + 1) is 15, so formulas can be copied the way textbooks print them.
• Open brackets close themselves. (2 + 3 already shows 5, so a forgotten bracket at the end does no harm.
• Very large numbers can be typed as 1e3 for 1,000, and answers of 1e15 or more are shown that way: 2^50 reads 1.12589991e+15.

One trap: the calculator reads a comma as a decimal point, so 2,5 is 2.5. That also means 1,000 is read as 1. Type large numbers without separators, or with spaces: 1 000 is one thousand. Dividing by zero shows “Nothing can be divided by zero.” instead of an answer. For times, use * or ×, never the letter x, which the calculator does not know.

What each scientific key does

The inverse functions have no keys but can be typed: asin(0.5) is 30 in degrees, and acos and atan work the same way. For a root other than the square root, raise to a fraction: 27^(1/3) is 3. For a logarithm in another base, divide two logs: ln(1024) / ln(2) is 10. Factorials go up to 170!; anything larger is too big to hold and shows Infinity.

Percent works the way a receipt does

The % key reads a percentage the way people say it out loud. Added or taken away, it is a share of the number before it; anywhere else it simply means hundredths:

• 200 + 10% = 220, and 200 − 10% = 180
• 200 × 10% = 20, the same as 10% of 200
• 200 ÷ 10% = 2,000
• 50% on its own = 0.5

Chains are worked from left to right, each percentage applying to the running total. 100 − 20% − 10% is 72, not 70: the second 10% comes off 80. That is exactly how stacked shop discounts behave, which the discount calculator page explains, and it is why a price that rose 10% twice is up 21%, not 20% (200 + 10% + 10% = 242). For the three classic questions, a percent of a number, what percent one number is of another, and the change from one value to the next, the percentage calculator sets them out side by side.

When the answer looks wrong

Most surprising answers come from one of these:

• The angle mode. sin 30 is 0.5 in Degrees but −0.9880316241 in Radians. Check the button beside Scientific before trusting any trigonometry result.
• tan 90°. It has no value, but π/2 cannot be stored exactly, so the calculator shows a huge number (1.63312394e+16) instead of an error.
• Roots of sums. √16 + 9 is 13, because the root takes only the 16. Write √(16 + 9) for 5.
• Tiny binary leftovers. Computers store 0.1 as a close approximation. The calculator rounds answers to 12 significant digits, so 0.1 + 0.2 shows 0.3 rather than 0.30000000000000004.

What it does not do: there is no graphing, no programmer mode and no memory keys (the history does that job). For binary and hexadecimal, use the number base converter in the Dev Toolbox.