Considering we should solve a question in 1 minute and also by 1 read (to not to procrastinate later about time insufficiency); we should have some shortcuts for typical problems..
Suppose you have 3 new members added to a team of 7, and you gotta find out no.of communication channels added?
Are you gonna solve this way -
Formula = n(n-1)/2
Total members now = 7+3 = 10
10(10-1)/2 - 7(7-1)/2 = 5*9 - 7*3 = 45 - 21 = 24
Hope you found out a trick that there is a division by 2 but also two consecutive numbers in numerator as n and n-1 one of which is gonna be divisible by two..and you must perform division before multiplication as we gotta play with small numbers as much as possible..
Here's my real trick..the new formula ..
m(m-1)/2 +nm
m is added mem n is original mem
3(3-1)/2+3*7=3+21=24
I used the example so that you don't need to remember the formula..
Happy Calculating!
Suppose you have 3 new members added to a team of 7, and you gotta find out no.of communication channels added?
Are you gonna solve this way -
Formula = n(n-1)/2
Total members now = 7+3 = 10
10(10-1)/2 - 7(7-1)/2 = 5*9 - 7*3 = 45 - 21 = 24
Hope you found out a trick that there is a division by 2 but also two consecutive numbers in numerator as n and n-1 one of which is gonna be divisible by two..and you must perform division before multiplication as we gotta play with small numbers as much as possible..
Here's my real trick..the new formula ..
m(m-1)/2 +nm
m is added mem n is original mem
3(3-1)/2+3*7=3+21=24
I used the example so that you don't need to remember the formula..
Happy Calculating!
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