Let's roll up our sleeves and solve this. We have 800 and we're going to multiply it by 19, essentially adding 800 to itself 19 times.
Step 1: 0 + 800 = 800
Step 2: 800 + 800 = 1600
Step 3: 1600 + 800 = 2400
Step 4: 2400 + 800 = 3200
Step 5: 3200 + 800 = 4000
Step 6: 4000 + 800 = 4800
Step 7: 4800 + 800 = 5600
Step 8: 5600 + 800 = 6400
Step 9: 6400 + 800 = 7200
Step 10: 7200 + 800 = 8000
Step 11: 8000 + 800 = 8800
Step 12: 8800 + 800 = 9600
Step 13: 9600 + 800 = 10400
Step 14: 10400 + 800 = 11200
Step 15: 11200 + 800 = 12000
Step 16: 12000 + 800 = 12800
Step 17: 12800 + 800 = 13600
Step 18: 13600 + 800 = 14400
Step 19: 14400 + 800 = 15200

So, 800*19 = 15200