2. both are ok. 2 times 2 10 is 420; 2 10 times 2 equals 420.

3." = "You can use" yes "or" equal ". There is no difference.

4.8 is twice as much as 2.

5. 1204 point three nine seven; Or use "dot"

6. You can use over to indicate that 33 is above 89, which is very vivid. You can also divide 33 by 89.

7.BC is used in BC, and AD is used after AD, directly after the number.

The sixth power of 8.8 can be said to be the sixth power of 8; The square root of 7 can be said under the root sign, and the square root of 4 plus 5 can be said under the root sign.