# `mulh`

[RISC-V Documentation](https://asm-editor.specy.app/documentation/risc-v.md) › [Instructions](https://asm-editor.specy.app/documentation/risc-v/instruction.md)

Web page: https://asm-editor.specy.app/documentation/risc-v/instruction/mulh

**Multiply high (signed × signed)**

Category: Arithmetic

Multiplies the second register by the third, both signed, and stores the high register-width bits of the product in the first.

[RISC-V manual: mulh](https://docs.riscv.org/reference/isa/v20260120/unpriv/m-st-ext.html#norm:mulh_mulhu_mulhsu_op)

Used in: [Arithmetic, logic and bits](https://asm-editor.specy.app/learn/courses/risc-v/think-in-assembly/arithmetic-logic-and-bits.md) (RISC-V assembly), [Multiply and divide, with the remainder](https://asm-editor.specy.app/learn/courses/risc-v/examples/multiply-and-divide.md) (RISC-V assembly)

## Forms

- `mulh t1, t2, t3`

## Operands

- `t1`: Any integer register, `x0` to `x31`, or its named alias, such as `zero`, `t0` or `t6`.
- `t2`: An integer register. It may be the same register as `t1`.
- `t3`: An integer register. It may be the same register as `t1`.

## Example

```riscv
.text
li t0, -2147483648
li t1, 2
# t0=-2147483648 and t1=2; the high product is -1; mulh writes -1 (0xFFFFFFFF) to t2.
mulh t2, t0, t1
```