Chứng tỏ rằng :  ab+ba chia hết cho 11 ; abc-cba chia hết cho 99  

mình viết về trò chơi nhé

there are a lot of interesting game suck as rollerblading, skipping,..but my favourite game is hide-and-seek. I usually play it with my friend on saturdays. The game last about 30 minutes. It is an inexpensive and easy game. You only need three or more persons. First, we have to find someone who will blindfold. Next, the blindfold will count from 1 to 10, the others will hide. After the blindfold was finished counting to 10, then that person will open their eyes to find the hider. If he or she find out everybody, they will start a new game. If seeker doesn't get all the hiders, the seeker will have to say " give up " and continue to play a new game. You should play it more because it can keep you entertained after the lessons at school and it's good for health