{
  "id": "round-to-the-nearest-tenth",
  "version": "c64e076b8c2a",
  "status": "published",
  "name": "Round to the Nearest Tenth Calculator",
  "question": "Round to the nearest tenth?",
  "summary": "Rounds any number to the nearest tenth (one decimal place) in exact decimals, and says which digit decides.",
  "category": "math",
  "subcategory": "arithmetic",
  "url": "https://www.acalculator.org/math/round-to-the-nearest-tenth-calculator",
  "markdown": "https://www.acalculator.org/math/round-to-the-nearest-tenth-calculator.md",
  "kind": "function",
  "method": "Look at the hundredths digit: 5 or more rounds the size of the number up to the next tenth; less than 5 keeps the tenths digit. Every digit to the right is dropped.",
  "assumptions": [
    "The number is taken as the decimal it is written as, so an exact halfway value is a true tie.",
    "Halves round away from zero (round half up on the size of the number): a negative number rounds like its size, with the minus sign kept."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "number": {
        "title": "Number to round",
        "description": "The number to round, as you would write it.",
        "type": "number"
      }
    }
  },
  "outputs": {
    "rounded": {
      "label": "Rounded number",
      "description": "The number rounded to the nearest tenth; halves round away from zero.",
      "format": "number"
    },
    "rule": {
      "label": "Why",
      "description": "The digit to the right of the tenths place, and what it does.",
      "format": "text"
    },
    "typed": {
      "label": "Number",
      "description": "The number to round, with every digit as typed, so the answer does not round it first.",
      "format": "text"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "number": 18.379
    },
    "outputs": {
      "rounded": 18.4,
      "rule": "The hundredths digit is 7, which is 5 or more, so the tenths digit goes up by 1.",
      "typed": "18.379"
    },
    "text": "18.379 rounded to the nearest tenth is 18.4."
  },
  "examples": [
    {
      "given": {
        "number": 18.379
      },
      "expect": {
        "rounded": 18.4,
        "rule": "The hundredths digit is 7, which is 5 or more, so the tenths digit goes up by 1."
      },
      "source": "OpenStax, Prealgebra 2e, section 5.1 Decimals (round 18.379 to the nearest tenth: 18.4), https://openstax.org/books/prealgebra-2e/pages/5-1-decimals (retrieved 2026-11-01)"
    },
    {
      "given": {
        "number": 3.14159
      },
      "expect": {
        "rounded": 3.1,
        "rule": "The hundredths digit is 4, which is less than 5, so the tenths digit stays."
      },
      "source": "hand calculation in content.mdx; OpenStax, Prealgebra 2e, section 5.1 Decimals (round 18.379 to the nearest tenth: 18.4), https://openstax.org/books/prealgebra-2e/pages/5-1-decimals (retrieved 2026-11-01)"
    },
    {
      "given": {
        "number": 1.45
      },
      "expect": {
        "rounded": 1.5
      },
      "source": "hand calculation in content.mdx: the hundredths digit is 5; OpenStax, Prealgebra 2e, section 5.1 Decimals (round 18.379 to the nearest tenth: 18.4), https://openstax.org/books/prealgebra-2e/pages/5-1-decimals (retrieved 2026-11-01)"
    },
    {
      "given": {
        "number": -2.25
      },
      "expect": {
        "rounded": -2.3
      },
      "source": "hand calculation in content.mdx: 2.25 rounds to 2.3 and the minus sign stays; OpenStax, Prealgebra 2e, section 5.1 Decimals (round 18.379 to the nearest tenth: 18.4), https://openstax.org/books/prealgebra-2e/pages/5-1-decimals (retrieved 2026-11-01)"
    },
    {
      "given": {
        "number": 9.96
      },
      "expect": {
        "rounded": 10
      },
      "source": "hand calculation in content.mdx; OpenStax, Prealgebra 2e, section 5.1 Decimals (round 18.379 to the nearest tenth: 18.4), https://openstax.org/books/prealgebra-2e/pages/5-1-decimals (retrieved 2026-11-01)"
    },
    {
      "given": {
        "number": -0.04
      },
      "expect": {
        "rounded": 0
      },
      "source": "hand calculation in content.mdx: the hundredths digit is 4, so the tenths digit stays 0; OpenStax, Prealgebra 2e, section 5.1 Decimals (round 18.379 to the nearest tenth: 18.4), https://openstax.org/books/prealgebra-2e/pages/5-1-decimals (retrieved 2026-11-01)"
    }
  ],
  "sources": [
    "OpenStax, Prealgebra 2e, section 5.1 Decimals (how to round decimals; 18.379 to the nearest tenth is 18.4). Retrieved 2026-11-01. https://openstax.org/books/prealgebra-2e/pages/5-1-decimals"
  ],
  "related": [
    "rounding",
    "round-to-the-nearest-thousand",
    "percentage"
  ],
  "changelog": []
}