The average of 7 consecutive numbers is 20. The largest of these numbers is-

Let the number be x, x + 1, x + 2, x + 4, x + 5 and x + 6
Then,
$$ \Rightarrow \frac{{x + \left( {x + 1} \right) + \left( {x + 2} \right) + \left( {x + 3} \right) + \left( {x + 4} \right) + \left( {x + 5} \right) + \left( {x + 6} \right)}}{7} = 20$$
$$\eqalign{ & \Rightarrow 7x + 21 = 140 \cr & \Rightarrow 7x = 119 \cr & \Rightarrow x = 17 \cr} $$

∴ Largest number
= x + 6 = 17 + 6
= 23