Question

look at the number sentences below 1+2+3+___+80=3240 71+72+___+80=755 what is the sum of the numbers from 1 to 70

Answer 1

$Given \: 1+2+3+\ldots +80 = 3240 \: --(1)$

$and \: 71+72+\ldots +80 = 755 \: --- (2)$

$Now, \red{ Sum \: of \: the \: numbers \:from }$

$\red{ 1 \:to \: 70 }$

$= \pink{(1+2+\ldots +80)}-\blue{(71+72+\ldots+80)}$

$= 3240 - 755$

$\green{ = 2485}$

Therefore.,

$\red{ Sum \: of \: the \: numbers \:from }$

$\red{ 1 \:to \: 70 }$

$\green{ = 2485}$

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Answer 2

The sum of the numbers from 1 to 70 is 2485.

Solution :-

• 1 + 2 + 3 + ___ + 80 = 3240 ----------(1)

• 71 + 72 + ___ + 80 = 755 -----------(2)

Now, Substracting equation (1) & (2) .

=> 1 + 2 + 3 + ___ + 80 - 71 + 72 + __ + 80

=> 3240 - 755

=> 2485 .