SrinathVangala wrote:
Hi clciotola..
(493)(915)(381)(756)(29)
For example .....
lets take \(13 * 15\) ...
we get 195.... You can see that If you multiply any odd number with 5 the units digit of the result will be 5.Why?
The last digit oof the odd number will be one of 1, 3, 5,7,9. If you multiply any of these digits with 5 you will get 5 as the units digit in the result.
Now lets take another example with an even number. take 12 * 15.
It is 180. Now 12 can be written as 2*6.Multiply 2 with 15 you will get 30.Now no matter what you multiply 30 with you will always get 0 in the units place.
So any even number when multiplied by 5 will give a result with 0 in the units place.
Lets get back to the question. If we muliptly 493 ,381 and 29 we will get an odd number
Let this result be x. so x is odd
If x is multiplied with an even number the result will be even right??(odd*even = even)
lets multiply x with 756. The result will be even.
Let this result be Y.
Now Y is an even number and you have to multiply it with 15. 15 has 5 in it.So the last digit in the result will be 0.
Hope this helps
(493) (915) (381) (756) (29)
Take 915 * 756, one has 6 and the other has 5 in units place. it will yield 0 (when multiplied 6*5 =30) at the end. Any number when multiplied with 10, 20, 30...100 would yield 0 in units place that is the case for this example.