Just to say I'm with 22B on this (though with the caveat that I have little experience with less mathy children); it seems to me far better for learning to use a crib sheet until its contents have been internalised than to use irrelevant mnemonics for maths facts, if those are the choices. Irrelevant mnemonics might get you through a test at a cost of long-term distraction.

Better, have relevant mnemonics, e.g., if squares are fine but 7x8 is a problem, know to take 7x7 and add one more 7. Most of my own facts feel less like things I know than like things I know how to work out really, really slickly. Dunno what fMRI would show!

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