Does anyone NOT know the 9 times table finger trick?

[DilemmaDelilah]

I was having lunch today with my DH and one of my grandchildren and we were idly trying to work out the weight of a McVities ginger cake. It doesn't have the weight on the packet, but it says that it has 9 portions each of 25.8g, so we were doing some mental arithmetic to work out the weight (for fun only... It wasn't performative grandparenting). Anyway - I was working it out the way that is easiest for me, which is to break the sum down into its component parts, i.e. 25x4, plus 25x4, plus 25, then 8 x 9 and add in the decimal point, then add them altogether which is, apparently, the autistic way (I am autistic) but seems ultra logical to me. This involved, obviously, working out 8x9. I did my usual finger trick to remember the answer and neither DH nor my grandson has ever heard of it!

It uses the fingers of both hands as a reminder. Bend down the first finger, that leaves 9 fingers, that means 1 x 9 is 9. Bend down the second finger, that leaves 1 finger and 8 fingers = 18, therefore 2 x 9 is 18. Bend down the third finger, that leaves 2 fingers and 7 fingers = 27, therefore 3 x 9 is 27 and so on....I thought this was something everyone knew, but apparently not! How about you lot? And does anyone else have any equally easy ways of remembering maths? My DH and grandson thought it was magic!

I never found 9 x table hard to remember because, as pps have said, the first digit goes up one every time and the second down one.

I was a year 5/6 teacher for 10 years and still use this trick to check my maths.

I always struggled to memorise them as a child and had to include little tricks to be able to answer fluently.

@Pandimoanymum and anyone else without ten fingers for any reason, I'm sorry I was assuming everyone had the same number of fingers which was insensitive and crass of me. I was talking to my grandson today about differences and different abilities as he is colour blind and his brother is autistic, so you would think that I would think before I type!

The 9 times finger method does only work for people with ten fingers.

Hey, no worries, honestly! It wasn’t insensitive or crass at all! I probably shouldn’t have mentioned not having enough fingers, since it has no bearing on why I’ve never heard of it. We were just never taught it. I just thought ‘not having enough fingers’ sounded quite amusing 🤣

Never heard of it but I know that they go and 0123456789 and 9,8,7,6,5,4,3,2,1 so it’s easy to do I don’t need to work it out I just know them

I learnt this at primary school and still use it over 40 years later!

That sounds unbearably complex OP. I'm with the x10-1 party.

That made me laugh.
I often tell people that we didn’t learn a lot of grammar, but I know most of The Beatles playlist.

@Pandimoanymum
On the plus side if you have 9 fingers / thumbs and ever find yourself calculating in base 9 - the same 'trick' will still work for the 8 times table!

e.g. 4 x 8 = 35 (which is worth 32 in base 10 as 3 x 9 = 27 + 5 = 32!)

Or just 10*25.8 - 25.8 =258-26+0.2 =232 + 0.2 = 232.2

Fingers not required.

I did finger trick at school.

Exactly this, I was berated by my teachers for about three years in primary school for being unable to get the hang of memorising times tables, but like you I think it gave me a better understanding of numbers.

Certainly no teacher cared about times tables once I got to secondary and consistently got top grades in maths (A* maths and A further maths at A level).

I definitely used the 9x finger trick in the non calculator paper at A level, along with doing long multiplication the 'wrong' way (Napier's bones).

I learnt this a few weeks ago watching Numberblocks with my toddler DS, and thought it was pretty amazing. I'd have just multiplied by 10 and taken away one portion though - possibly doing the 25 and the .8 separately.

On a completely different note, Johnny Ball came and did a leavers' assembly at my secondary school and basically told all the kids that smoking isn't that bad for you. Not really the message I'd have gone for.

I was once told there are at least three ways to solve every maths problem. For me that’s a multiply by ten then minus the 25.8. Nine times table is one of the easiest to remember as adds up to 9 apart from 11/ 12. I think the way they teach times tables is 0,1, 10, 2, 5, 9, 4, 6, 8, 3 then 7 so they come in order of difficulty.

I'm the opposite, I find learning tricks, mnemonics etc. far harder than whatever it's meant to help me learn in the first place.

I know this trick and is very helpful!

Got it! Thanks :-)

You didn't say to put the first finger back up again, you see!

Anyway, I asked my 16 yo son this morning and he was shocked I didn't know the finger trick.