Struggling with the nine times table? I have a failsafe method (www.theguardian.com)

submitted 4 days ago by Aatube@lemmy.dbzer0.com to c/nottheonion@lemmy.world

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Apparently, nines are the hardest to grasp for primary school children. If only they’d learned how to cheat like me, says Adrian Chiles

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[-] Bytemeister@lemmy.world 2 points 2 days ago

1-9 by 9 is easy though.

Take the first number, subtract 1 from it, and that will be your 10's place. Your 1's place with be whatever that first number needs added to it to get to nine.

Example... 7x9. 7-1= 6, so 60. 9-6=3. Answer is 63.

Another fun math trick while we're at it. If you want to know if a number is divisible by 3, just add up all the digits, and if that number is divisible by 3, then so is your original number. 3135...3+1+3+5=12, so 3135 is divisible by 3.

[-] BradleyUffner@lemmy.world 1 points 2 days ago

This is how I learned it too. The digits always have to add up to 9.

this post was submitted on 23 May 2026

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