index.md

---

title: Population count
slug: WebAssembly/Reference/Numeric/Population_count

---

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The popcnt instructions, short for population count, are used to count the amount of 1s in a numbers binary representation.

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Syntax

;; load a number onto the stack
i32.const 130 ;; 10000010

;; count the 1s
i32.popcnt

;; the top item on the stack will now be 2

Instruction	Binary opcode
i32.popcnt	0x69
i64.popcnt	0x7b