Now I can have more fun when grading ;).
<Multi_key> <asciicircum> <plus> : "⁺" U207A # SUPERSCRIPT PLUS
<Multi_key> <asciicircum> <minus> : "⁻" U207B # SUPERSCRIPT MINUS
<Multi_key> <asciicircum> <plus> : "⁺" U207A # SUPERSCRIPT PLUS
<Multi_key> <asciicircum> <minus> : "⁻" U207B # SUPERSCRIPT MINUS
+<Multi_key> <c> <plus> : "✓" U2713 # CHECK MARK
+<Multi_key> <c> <x> : "✗" U2717 # BALLOT X
+
<Multi_key> <A> <A> : "∀" U2200 # FOR ALL
<Multi_key> <d> <d> : "∂" U2202 # PARTIAL DIFFERENTIAL
<Multi_key> <E> <E> : "∃" U2202 # THERE EXISTS
<Multi_key> <A> <A> : "∀" U2200 # FOR ALL
<Multi_key> <d> <d> : "∂" U2202 # PARTIAL DIFFERENTIAL
<Multi_key> <E> <E> : "∃" U2202 # THERE EXISTS