With pointer finger extended over extended thumb, tap pointer finger onto thumb twice, near other extended pointer finger. Then flick hand upwards in an arc.
Start palm facing upwards, and pointer and thumb tips touching. Move hand upwards while twisting hand over so that palm faced downwardly. Tap pointer fingertip against thumb tip twice.
Start signing eleven (Tap pointer fingertip to extended thumb tip twice) Twisting hand over, and draw hand downwards, so that you end with palm facing upwards and pointer and thumb tips still touching.