Let's roll up our sleeves and solve this. We have 799 and we're going to multiply it by 10, essentially adding 799 to itself 10 times.
Step 1: 0 + 799 = 799
Step 2: 799 + 799 = 1598
Step 3: 1598 + 799 = 2397
Step 4: 2397 + 799 = 3196
Step 5: 3196 + 799 = 3995
Step 6: 3995 + 799 = 4794
Step 7: 4794 + 799 = 5593
Step 8: 5593 + 799 = 6392
Step 9: 6392 + 799 = 7191
Step 10: 7191 + 799 = 7990

So, 799*10 = 7990