To answer your question about the little number on the top right corner of another number or bracket is an exponent, An exponent is a short cut for writing multiplying many things that are the same together. The exponent tells us how many times each thing that is the same is multiplied.
For example: 2⁴=2x2x2x2 = 16. The exponent 4 tells us that 2 is multplied by itself 4 times.

When expressions have more than one operation, we have to follow rules for the order of operations which is also known as BEDMAS:

Brackets - First do all operations that lie inside brackets (also known as parentheses).
Exponents - Next, do any work with exponents or radicals.
Multiplication & Division - Working from left to right, evaluate any multiplication and division.
Addition & Subtraction - Finally, working from left to right, do all addition and subtraction.

An example of an expression with all of the above operations is 4 x (6-2)²÷(3-1)³-7

4 x (6-2)2÷(3-1)3-7
4 x (4)2÷(2)3-7	First I worked inside the brackets: 6-2=4 and 3-1=2
4 x 16÷8-7	Next I worked with my exponents: 42=4x4=16 and 23=2x2x2=8
64÷8-7	Working from left to right, I multiply and divide: 4x16=64
8-7	Working from left to right, I multiply and divide:64÷8 = 8
1	Last I add or subtract: 8-7=1

Remember that when you are working within the brackets to also follow the BEDMAS rules. For example: 4x[3²-(4+5)]

4x[32-(4+3)]
4x[32-7]	First I worked inside the brackets and notice another set of brackets so I will start there first: 4+3=7
4x[9-7]	Next I worked with my exponent within the bracket: 32=9
4x2	Next there is no multiplication or division in the brackets so I will subtract: 9-7=2
8	The only operation that is left is multiplication: 4x2=8

Hope this helps. Good luck with the new school year!

Janice