Question

Find the sum of first 40 odd natural numbers??

Answer 1

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step 1

Address the formula, input parameters & values.

Input parameters & values:

The number series 1, 3, 5, 7, 9, . . . . , 79.

The first term a = 1

The common difference d = 2

Total number of terms n = 40

step 2

apply the input parameter values in the AP formula

Sum = n/2 x (a + Tn)

= 40/2 x (1 + 79)

= (40 x 80)/ 2

= 3200/2

1 + 3 + 5 + 7 + 9 + . . . . + 79 = 1600

Therefore, 1600 is the sum of first 40 odd numbers.

Thanks

Answer 2

Answer:

The Sum of the first 40 odd numbers is 1600.

Step-by-step explanation:

The odd number series is  1 ,3, 5, 7 ,9-----, 77, 79.

Common difference (d) = 3 -1 = 2

And  first number (a) = 1

Total number of terms($T_n$) =  40

The given series is in A. P

Sum of numbers  $= \frac{n}{2} \times (a + T_n)$

Put the values

$= \frac{40}{2} \times (1 + 79)\\= \frac{(40 \times 80)}{2} \\ =\frac{3200}{2} \\= 1600$

Hence,

1 + 3 + 5 + 7 + 9 + .  .  .  .   + 79 = 1600

Sum of first 40 odd numbers is 1600.