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round

Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Returns the given number rounded to the specified precision

namespace HH\Lib\Math;

function round(
  num $val,
  int $precision = 0,
): float;

A positive precision rounds to the nearest decimal place whereas a negative precision rounds to the nearest power of ten. For example, a precision of 1 rounds to the nearest tenth whereas a precision of -1 rounds to the nearest ten.

Parameters​

  • num $val
  • int $precision = 0

Returns​

  • float

Examples​

$round1 = Math\round(8.65);
echo "8.65 rounded to default precision 0 yields $round1 \n";

$round2 = Math\round(8.65, 1);
echo "8.65 rounded to precision 1 yields $round2 \n";

$round3 = Math\round(8.65, -1);
echo "8.65 rounded to precision -1 yields $round3 \n";