Khi $\ast$ là các chữ số $0$; $2$; $4$; $6$; $8$ thì số $\overline{2\ast }$ chia hết cho $2$.

khi $\ast$ là các chữ số $1$; $7$ thì số $\overline{2\ast }$ chia hết cho $3$.

khi $\ast$ là các chữ số $5$ thì số $\overline{2\ast }$ chia hết cho $5$ nên số $\overline{2\ast }$ là hợp số.

Khi $\ast$ là $3$ hoặc $9$ thì $\overline{2\ast }$ là $23$ hoặc $29$ là các số nguyên tố.

A = 2011 + 2012 + 2013 + 2014 + 2015 + 2016 + 2017 + 2018 + 2019.

   =(2011+2019) + (2012 +2018) + (2013+2017) +(2014 +2016) + (2015+2015) 

    = 4030 + 4030 + 4030+ 4030+4030

    = 4030 .5

    = 20150

15m vuông

giống nhau

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vbnm

Hi Susan,

I hope you're well! I want to share a bit about my neighbourhood. I live in a quiet neighbourhood on the outskirts of town. It's really nice here. There are green parks, a small lake, and some small shops nearby. The best part is how peaceful it is. I love the greenery and friendly neighbours. Living here is great because it's calm and convenient at the same time.

Please write and tell me about your neighbourhood.

Love,

Vicky

1. She/ long black / big eyes.…………………………………………………………………………………

2. I/ like/ live/ my neighbourhood/ because/ it/ quiet……………………………………………………………

3. Lan/ walk/ ride/ bike / school?…………………………………………………………………….

4. My neighbourhood / noisy/ your neighbourhood……………………………………………………………* 

7w

t58;ơp