How can you use a pattern to add 20+30+40+50+60+70+80

Question

asked Oct 8, 2020 21.0k views

1 Answer

Rising Lee · Answer 1 · 2020-10-14T21:24:23+0000

Answer:

$\displaystyle \: \: \: \: 7 \\ \: \: \sum \: (10n + 10) \\ n = 1$

Explanation:

You can use Summation Notation as a pattern to evaluating "20 + 30 + 40 + 50 + 60 + 70 + 80":

$\displaystyle \: \: \: \: 7 \\ \: \: \sum \: (10n + 10) \\ n = 1$

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