Let's roll up our sleeves and solve this. We have 990 and we're going to multiply it by 5, essentially adding 990 to itself 5 times.
Step 1: 0 + 990 = 990
Step 2: 990 + 990 = 1980
Step 3: 1980 + 990 = 2970
Step 4: 2970 + 990 = 3960
Step 5: 3960 + 990 = 4950

So, 990*5 = 4950