The experts of Jagranjosh.com have evolved forward to help the aspirants in attempting all the questions speedily with basic preparatory strategy. By providing basic concepts, we are trying to make the calculation faster than doing from long and traditional ones. Practice and thorough learning of some values can help the candidates in cracking Quantitative Aptitude/Numerical Ability Section in Bank Exam, SSC Exam, Railway and Other Exam.
We have come up with some Time Saving Methods in Multiplications, which will make your calculations more speedy and faster.
Multiplication by 5, 25 & 125
1. For multiplication by 5
As we know that 5=10/2. Multiply the figure given by 10 and then divide it by 2.
For example: 3568 x 5 = 35680/2 = 17840.
It is considered as a very simple method. The adoption of this method saves 5 seconds. If one adopts such methods at a number of places in the entire exam. It will save even 4 to 5 minutes that helps you attempt at least 115 more questions. This itself may make all the difference to your chances of selection.
2. For multiplication by 25
Similarly, We know 25=100/4. So multiply the figure given by 100 and divide it by 4.
For Example 3568 x 25 = 356800/4=89200.
3. For multiplication by 125
We know 125=1000/8. So multiply the figure given by 1000 and divide it by 8.
For Example 3568 x 125 = 3568000/8 = 446000. Alternatively, if we write 125 as 100 + 25, it is correct. So, multiplication by 125 can be treated as multiplication by 100 and add to this figure one- fourth of itself (because 25 is one-fourth of 100).
4. For multiplication by 11, 21, 31 etc
It can be treated as multiplication by 10+1, 20+1, 30+1, etc..
For Example 3568 × 11 3568 X (10+1) = 39248
5. Multiplication by 19, 29, 39 etc
It can be treated as multiplication by (20 - 1), (30-1), (40-1) etc...
For Example 3568 x 19 = 3568 x 20 – 3568 = 67792
If you have any Question/Point on the above information, please ask/discuss it in the Banking Group
If you have any Question/Point on the above information, please ask/discuss it in the SSC Group