Math Notebook

>=4.6

Calculator-style notepad inspired by Numi. Write expressions in natural language — results appear instantly on every line.

Arithmetic

Standard math operators and parentheses.

10 + 5          → 15
20 * 3          → 60
(2 + 3) * 4     → 20
2 ^ 10          → 1,024
5 300           → 5,300

Word Operators

Use words instead of symbols.

Operation	Keywords
Addition	plus, and, with
Subtraction	minus, subtract, without
Multiplication	times, multiplied by, mul
Division	divide, divide by
Modulo	mod

8 times 9           → 72
100 plus 50         → 150
200 without 30      → 170
10 multiplied by 3  → 30
17 mod 5            → 2

Variables

Declare variables with = and reuse them across lines.

v = 20          → 20
v times 7       → 140
v + 10          → 30

Labels

Prefix a line with a label followed by a colon — the label is ignored, only the expression is evaluated.

Price: $11 + $34.45     → 45.45 USD
Monthly: 1200 / 12      → 100

Inline Quotes

Text inside double quotes is ignored.

$275 for the "Model 227"   → 275 USD

Percentage

Basic percentage

100 + 15%       → 115
200 - 10%       → 180
15% of 200      → 30

Advanced percentage

Operation	Example	Result
Adding percentage	5% on 200	210
Subtracting percentage	5% off 200	190
Percentage of one value relative to another	50 as a % of 100	50
Percentage addition relative to another	70 as a % on 20	250
Percentage subtraction relative to another	20 as a % off 70	71.43
Value by percent part	5% of what is 6	120
Value by percent addition	5% on what is 6	5.71
Value by percent subtraction	5% off what is 6	6.32

Scales

Shorthand for large numbers. One-letter scales are case-sensitive: k for thousands, M for millions.

$2k             → 2,000 USD
3M              → 3,000,000
1.5 billion     → 1,500,000,000
10 thousand     → 10,000

Currency

Supports ISO 4217 codes, common currency symbols, and common currency names. Live exchange rates with cached fallback.

Supported symbols

Symbol	Currency
$	USD
€	EUR
£	GBP
¥	JPY
₽	RUB
₴	UAH
₩	KRW
₹	INR
R$	BRL

Supported ISO codes

USD, EUR, GBP, CAD, RUB, JPY, CNY, CHF, AUD, KRW, INR, BRL, MXN, PLN, SEK, NOK, DKK, CZK, HUF, TRY, NZD, SGD, HKD, ZAR, THB, UAH, ILS.

$30 + $15                → 45 USD
$30 to EUR               → ... EUR
€50 + £20                → ... EUR
5 dollars + 10 dollars   → 15 USD

Unit Conversion

Powered by mathjs. Use to, in, as, into for conversion.

5 km to mile                → 3.10686 mile
5 km into mile              → 3.10686 mile
1 inch in cm                → 2.54 cm
100 celsius to fahrenheit   → 212 fahrenheit
1 kg to lb                  → 2.20462 lb
1 meter 20 cm               → 1.2 m
1 meter 20 cm into cm       → 120 cm
1 point to inch             → 0.0138889 inch
1 are to m^2                → 100 m^2
1 degree to radian          → 0.0174533 radian
1 nautical mile to mile     → 1.15078 mile

Supported unit categories

• Length: meter, inch, foot, yard, mile, nautical mile, point, line, hand, furlong, cable, league, etc.
• Weight: gram, kg, pound, ounce, tonne, stone, carat, etc.
• Temperature: celsius, fahrenheit, kelvin
• Time: second, minute, hour, day, week, month, year
• Angular: radian, degree, and °
• Data: bit, byte, KB, MB, GB, TB (with SI and binary prefixes)
• Area: m², hectare, acre, are, plus aliases like sq, square, sqm
• Volume: liter, gallon, pint, quart, cup, teaspoon, tablespoon, plus aliases like cu, cubic, cb, cbm

CSS Units

Supports CSS-oriented px, pt, and em conversions with configurable ppi and em.

12 pt in px       → 16 px
em = 20px
1.2 em in px      → 24 px
ppi = 326
1 cm in px        → 128.35 px

Math Functions

sqrt(16)        → 4
sqrt 16         → 4
cbrt 8          → 2
root 2 (8)      → 2.8284
sin(45 deg)     → 0.7071
sin 45°         → 0.7071
cos(pi)         → -1
log(100)        → 2
log 2 (8)       → 3
ln(e)           → 1
abs(-42)        → 42
round(3.7)      → 4
round 3.45      → 3
ceil(3.2)       → 4
floor(3.9)      → 3
fact(5)         → 120
arcsin(1)       → 1.5708
arccos(1)       → 0
arctan(1)       → 0.7854

Number Formats

Append in hex, in bin, in oct, or in sci to format the result.

255 in hex      → 0xFF
10 in bin       → 0b1010
255 in oct      → 0o377
5300 in sci     → 5.3e+3
5 300 in sci    → 5.3e+3

Input also supports hex, binary, and octal literals:

0xFF            → 255
0b1010          → 10
0o377           → 255

Previous Result

Use prev to reference the result from the previous line.

10 + 5          → 15
prev * 2        → 30
prev - 5        → 25

Sum & Total

sum or total calculates the sum of all numeric results above (until an empty line).

10 + 5          → 15
20 * 3          → 60
sum             → 75

Average

average or avg calculates the mean of all numeric results above (until an empty line).

10
20
30
average         → 20

Comments

Lines starting with // or # are treated as comments and produce no result.

// This is a comment
# This is also a comment

Date & Time

Convert Unix timestamps to dates with fromunix.

fromunix(1446587186)    → 11/3/2015, ...
fromunix(1446587186) + 2 day

Time arithmetic follows Numi-like semantics: 1 year = 365 days, 1 month = 365 / 12 days.

Current time helpers:

time
time()
now
now()
now in Madrid
Berlin now
time() + 1 day
now + 1 day

Time zone conversion:

PST time
New York time
Time in Madrid
2:30 pm HKT in Berlin
2:30 pm New York in Berlin
2026-03-06 PST in Berlin
2026-03-06 2:30 pm PST in Berlin
Mar 6 2026 PST in Berlin
2:30 pm Mar 6 2026 PST in Berlin
tomorrow PST in Berlin

Time unit arithmetic:

1 month in days          → 30.4167 days
round(1 month in days)  → 30
round 1 month in days   → 30
2 hours + 30 minutes    → 2.5 hours

Constants

Name	Value
pi	3.1415926536
e	2.7182818285

Bitwise Operations

5 & 3           → 1
5 | 3           → 7
5 xor 3         → 6
1 << 4          → 16
16 >> 2         → 4
6 (3)           → 18

SI Prefixes

SI-based units support all SI prefixes (case-sensitive):

1 mm            → 0.001 m
3 GB            → 3e+9 bytes
2 MHz           → 2,000,000 Hz