2²-6⁷+8³=

2² = 2 x 2 = 4

6⁷ = 6 x 6 x 6 x 6 x 6 x 6 x 6 = 279,936

8³ = 8 x 8 x 8 = 512

Now substituting these values into the equation:

2² - 6⁷ + 8³ = 4 - 279,936 + 512

Now we can simplify the equation further:

4 - 279,936 + 512 = -279,420

Therefore, the value of 2² - 6⁷ + 8³ is -279,420.