: III. Complete the passage, using the correct form of tense of the verbs in brackets.Nowadays, a lot of important inventions (1) ................... (carry out) by scientists (2) ....................... (work) for large industrials firms. However, there (3) .................... (be) still opportunities for other people (4) .................... (invent) various things. In Britain, there is a weekly TV program which (5) ................. (attempt) to show all the devices which people (6) ................ (invent) recently. The people (7) ..................... (organize)the program receive information about 700 inventions per year. New ideas can (8) .................... (develop) by private inventors. However, it is important (9) ....................... (consider) these questions : Will it work? Will it (10) ................. (want)? Is it new?

Xét tổng 888...8+n(n chữ số 8)

Ta có 888...8(n chữ số 8) có tổng các chữ số là 8n

Nếu 888...8+n(n chữ số 8) chia hết cho 9 thi 8n+n phải chia hết cho 9 hay 9n chia hết cho 9(luôn đúng)

=>888...8+n(n chữ số 8) chia hết cho 9

=>888...8+n(n chữ số 8)-9 chia hết cho 9(đpcm)

đó chính là NGUYỂN NGỌC KÝ

song

số bé 44 số lớn 96