fx-82MS fx-82TL fx-9860GII TI-83
INS
On a TI calculator you can insert a digit or function at the current cursor position
INS 2nd DEL
and the blinking insert cursor ░ will then be displayed. By pressing again or with ENTER you come back to the normal cursor.
Example 1
To change the calculation 1 + 
to 1 + 
where the blinking input cursor ░ is displayed
INS 1+░/6 √ I 1+√(7/6 ◄ ◄ ◄ 2nd DEL 2nd x²