Question

Without adding, find the sum  (a) 2+ 3+ 5+ 7+ 9 +11+ 13

show the process and proof also please!!​

Answer 1

Answer:

49

Step-by-step explanation:

take no. of digits = n

now square it so n = 7

so the square of 7 is 49

so answer is 49

now subtract n from it

so answer is 42

Hope it helps you ;)

Answer 2

Answer:

Given 2+ 3+ 5+ 7+ 9 +11+ 13

we can write given sum as

=1+[1+3+5+7+9+11+13]

=1+[7²]. (sum of n odd numbers starting from 1 is =n²)

=1+49

=50.