Multiplication Finger Tricks

Some of us just need some help from our fingers.  Hopefully this is for you.

Multiplying on fingers

Yes, it can be done. Multiplying on fingers is not as easy as adding or subtracting with the fingers, and you do need first of all to know how to multiply low numbers by 2, 3, 4 and 5. But most children who have difficulties with multiplication have problems with the 6, 7 or 8 times table.
It's a bit complicated to remember what to do, and some children would find it more trouble than it's worth! However a child who learns kinesthetically and has difficulty remembering anything by rote would probably grasp this quickly. So do try this with your children, even if it seems highly complex from your adult point of view.

Here's what you do:

Hold your hands horizontally in front of you, with your elbows sticking out, palms facing away from you, tips of middle fingers touching. (That's the hardest part to describe in text!)
Mentally (or with marker pen) number the thumbs as 6, index fingers as 7, middle fingers 8, ring fingers 9, little fingers 10. And define the thumbs as honorary fingers for the purposes of this 'manual calculator'.
To do any multiplication, from 6x6 through to 9x9, touch two fingers together which represent the numbers you want to multiply. For instance, for 7x8, touch index finger of one hand to middle finger of the other.

Now comes the tricky part with finger multiplication

The two touching fingers and all the ones nearer to you than the ones touching are the 'tens' group. In the 7x8 example you have five: both thumbs, both index fingers and one middle finger are in that group, so the answer contains 5 tens.
The remaining number of fingers on each hand - in this case 3 on one hand and 2 on the other - must be multiplied together to give the 'units' of the answer. 3x2 = 6.
The answer to 7x8 is five tens and six units, 50+6 = 56.
It sounds horrendous, but some children love it and it really works.

One minor point about multiplying on fingers

Sometimes the 'units' add up to more than 10, in which case the ten must be 'carried' and added onto the other tens. For instance, if you multiply 6x7, you will have 3 tens (2 thumbs and one finger), with 3 and 4 fingers respectively remaining, and 3x4 is 12. So either add 12 to 30 and don't worry about it being units, or carry the 10 mentally and add 40 to 2 - either way you get 42.
It works for every multiplication from 6x6 to 10x10 (not that you'd want such a complex method for multiplying by 10 - if you think you do, try reading the page on multiplication tricks). 

Clicking on "page on multiplication tricks will take you to the page were this came from, with more math tips and help.


Wes