Let's roll up our sleeves and solve this. We have 407 and we're going to multiply it by 10, essentially adding 407 to itself 10 times.
Step 1: 0 + 407 = 407
Step 2: 407 + 407 = 814
Step 3: 814 + 407 = 1221
Step 4: 1221 + 407 = 1628
Step 5: 1628 + 407 = 2035
Step 6: 2035 + 407 = 2442
Step 7: 2442 + 407 = 2849
Step 8: 2849 + 407 = 3256
Step 9: 3256 + 407 = 3663
Step 10: 3663 + 407 = 4070

So, 407*10 = 4070