Question

how to calculate without pen paper or calculator, simply in mind,1000+40+1000+30+1000+20+1000+10=?

Answer 1

First of all add all the 1000 values and next add all ten values

Answer 2

First add 1000 in mind
U will simply get
4000
Then add 40,30,20 and 10
U will get
1000


Now add both the answer U will get 5000