Question

1+2+...+80 adding only ✓✓✓✓✓✓✓✓✓✓✓✓✓only​

Answer 1

Answer:

83

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Answer 2

Answer:

3240

Step-by-step explanation:

1+2+3+...+80

∑n from 1 to 80

n=80

80*(81)/2

40*81

3240