Adding Consecutive Numbers

ADDING CONSECUTIVE NUMBERS

Rule 
Step 1 : Add the smallest number in the group to the largest number in the group.
Step 2 : Multiply the result of step 1 by the amount of numbers in the group.
Step 3 : Divide the result of Step 2 by 2
Step 4 : Result of step 3 is your answer

Examples

Ex 1 : Add numbers from 21-38. 
step 1 : add 21+38 = 59
step 2 : total numbers between 21-38 = 38-21+1 = 18
            59 X 18
                 2
step 3 : 59 X 9 = 31 5
step 4 : Answer 315

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Ex 2 : Add numbers starting from 1 (like 1 to 56)
Shortcut : Multiply last number with It's one more number that divide it by 2
Solution of above problem is : 56 X 57 / 2
                                                 = 28 X 57
                                                 = 1596 Answer