The mean of 8 numbers is 35. If a number is excluded then the mean is reduced by 3.

Mean of 8 numbers = 35

Sum of 8 numbers $=35 \times 8=280$

Let the excluded number be x.
Now,
New mean = 35 -">−- 3 = 32
Thus, we have:

$\frac{\text { Sum of 8 numbers- } x}{7}=32$

$\Rightarrow \frac{280-x}{7}=32$

$\Rightarrow 280-x=224$

$\Rightarrow x=56$

Therefore, the excluded number is 56.