OK, let's crack this. We're given 790 and our task is to multiply it by 3. Essentially, we'll be adding 790 to itself 3 times.
Step 1: 0 + 790 = 790
Step 2: 790 + 790 = 1580
Step 3: 1580 + 790 = 2370

So, 790*3 = 2370