<u><em>Distributive property states that:</em></u>
a(b+c) = ab + bc
Therefore, to solve 5*198 using mental Math, we would need to break the 198 into simpler values and use distributive property to get the solution
198 can be written as 100 + 90 + 8
We can rewrite this as 100 + 10(9) + 8
<em><u>Now, for the given expression:</u></em>
5 * 198 = 5 (100 + 10(9) + 8)
<u><em>We apply the distributive property as follows:</em></u>
5(100) + 5(10)(9) + 5(8)
500 + 45(10) + 40
500 + 450 + 40
Now, we can simply do the addition giving us 990
Hope this helps :)