Jogeephus
Well-known member
Here is a little trick I thought some of you might find useful in everyday life. It has to do with a quirck in mathematics and you might find it helpful from time to time. I'll give you the basics of it but it can be expanded with a little ingenuity. First of all, whenever two two digit numbers say between 10 and 100 begin with the same number and the sum of the second two numbers add up to ten, this trick can be used flawlessly.
For instance, if you need to know the sum of 75 x 75, forget all the multiplication you have been taught and just multiply the two fives together to get the number 25. Next, add 1 to one of the 7's and you get 8. Multiply 8 x 7 and you get 56. Now jut put these two numbers together and you get 5625.
Take 83x87. 8x9=72 3x7=21 answer is 7221.
Take 91x99 9x10=90 9x1=09 answer is 9009.
Or what is the 75 squared? 56 25
Get the drift? But remember, the first two numbers HAVE to be the same and the last two HAVE to add up to 10. But once you get the hang of this, you can expand this even further to numbers that almost meet the rule.
Hope this is a worthwhile tip if not, maybe you can win a beer with it.
For instance, if you need to know the sum of 75 x 75, forget all the multiplication you have been taught and just multiply the two fives together to get the number 25. Next, add 1 to one of the 7's and you get 8. Multiply 8 x 7 and you get 56. Now jut put these two numbers together and you get 5625.
Take 83x87. 8x9=72 3x7=21 answer is 7221.
Take 91x99 9x10=90 9x1=09 answer is 9009.
Or what is the 75 squared? 56 25
Get the drift? But remember, the first two numbers HAVE to be the same and the last two HAVE to add up to 10. But once you get the hang of this, you can expand this even further to numbers that almost meet the rule.
Hope this is a worthwhile tip if not, maybe you can win a beer with it.