How do you multiply a whole number by a radical? Also, how do you ADD a whole number with a radical? Thanks!

You just write the number next to the radical when multiplying. For example...
5*√x = 5√x
You could always stick the number inside if you wanted to like this
√25x
Because a number and a radical aren't like terms the simplest form of the expression 5 + √x is the expression itself, 5 + √x. However, if you had something like 5√x + √x, the simplified form would be 6√x (think of it as there being a 1 outside the 2nd radical).
5*√x = 5√x
You could always stick the number inside if you wanted to like this
√25x
Because a number and a radical aren't like terms the simplest form of the expression 5 + √x is the expression itself, 5 + √x. However, if you had something like 5√x + √x, the simplified form would be 6√x (think of it as there being a 1 outside the 2nd radical).

for example,
2 times √3
is the same as
2(√1) times 1√3
multiply the outisde by outside, inside by inside
2(1) times √(1x3)
2 √3
If you're more confused about:
5 x 3√2
multiply the outside by the outside:
15√2
3 + √48
you can only simplify the radical.
3 + (√16 x 3)
3 + (4 x √3)
3 + 4√3
can't simplify further.
2 times √3
is the same as
2(√1) times 1√3
multiply the outisde by outside, inside by inside
2(1) times √(1x3)
2 √3
If you're more confused about:
5 x 3√2
multiply the outside by the outside:
15√2
3 + √48
you can only simplify the radical.
3 + (√16 x 3)
3 + (4 x √3)
3 + 4√3
can't simplify further.