# Set new tempo as a multiple of current tempo for block

``

    with_bpm_mul  mul (number)

Sets the tempo in bpm (beats per minute) for everything in the given block as a multiplication of the current tempo. Affects all containing calls to `sleep` and all temporal synth arguments which will be scaled to match the new bpm. See also `with_bpm`

Introduced in v2.3

## Example

# Example 1
``
    use_bpm 60
      play 50
      sleep 1
      play 62
      sleep 2
      with_bpm_mul 0.5 do
        play 50
        sleep 1
        play 62
      end
      sleep 1
| ``
    # Set the BPM to 60

    # Sleeps for 1 second

    # Sleeps for 2 seconds
    # BPM is now (60 * 0.5) == 30

    # Sleeps for 2 seconds

    # BPM is now back to 60, therefore sleep is 1 second