Decimal subtract

decimal-subtract · version 1.0.0 · Numbers & math · free, no key needed

Exact decimal subtraction a minus b of canonicalizable decimal strings.

Use when you need to: decimal subtract · subtract decimals · exact decimal difference.

Decide before calling

Read the versioned contract and the supported scope below. Reuse decimal-subtract@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use decimal-subtract@1.0.0 for decimal subtract. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• decimal subtract
• subtract decimals
• exact decimal difference

Not supported

• ieee754
• currency rounding
• tax

Behavior

• Input decimal strings: /^-?(0|[1-9][0-9]*)(\.[0-9]+)?$/.
• Reject leading zeros, plus signs, spaces, exponents, bare ".", trailing ".", empty, and NaN/Infinity tokens.
• At most 40 digits excluding sign and decimal point. At most 18 fractional digits on input.
• Canonicalize: strip trailing fractional zeros; drop the decimal point if the fraction vanishes; normalize -0 and -0.0 to "0".
• Exact decimal arithmetic with BigInt scaled integers. No IEEE-754 intermediates. Never return JSON BigInt.
• Return canonical a-b.

Input

• a (string, required): min length 1; max length 44
• b (string, required): min length 1; max length 44

Output

• value (string, required)

Limits

• max digits: 40
• max scale: 18

Example

Request input:

{
  "a": "2.00",
  "b": "0.1"
}

Response:

{
  "result": {
    "value": "1.9"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "decimal-subtract",
  "version": "1.0.0",
  "input": {
    "a": "2.00",
    "b": "0.1"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/decimal-subtract/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"a":"2.00","b":"0.1"}'

The machine-readable contract is at /v1/tools/decimal-subtract/versions/1.0.0.

CLI

node cli.mjs run decimal-subtract 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Decimal add: Exact decimal addition of canonicalizable decimal strings.
• Capacity allocation check: Check an exact claimed allocation for eligibility and per-bin decimal capacity compliance.
• Decimal compare: Compare two decimal strings exactly after canonicalization.
• Number engineering format: Format an exact decimal in scientific or engineering notation with explicit precision and rounding.
• Permutation ranked check: Check exact stable ordinal ranks for decimal-string values and nulls, reporting the first source-index discrepancy.
• Rational subtract: Subtract one rational number from another, given as numerator/denominator integer strings, and return the reduced difference.